HIDDEN HILLS, Calif. — On a top shelf of a built-in bookcase in a dark and donnish study of a home here sit several copies — some first editions — of a story about chasing stardom. It’s also a story about love versus obsession. Or maybe, most simply, it’s a rags-to-riches tale about a country kid who becomes famous in the big city.

“Great Expectations” is Jessica Simpson’s favorite book, but she hadn’t thought that her life story shares similar themes.

“Well, I’m glad I’m not Miss Dinsmoor” — the name of the rich but jilted spinster living in a rundown mansion in the 1998 movie — she said, “or Miss Havisham!” the name of the same character in the book.

I asked Ms. Simpson who had great expectations for her. “In your case, you, for sure,” said Lauren Auslander, Ms. Simpson’s publicist and close friend who, despite my request that she not, hovered during my interview with her client.

“Yeah, one hundred percent,” Ms. Simpson said softly, pulling on the drawstrings of her dark teal sweatsuit.

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When Jessica Simpson walks into a room you’re surprised by three things. The first, and they warn you about this — they say all celebrities are, but trust me, you can’t really wrap your brain around it until you are staring down at a strip of white scalp, bending a mile to give a perfunctory hug hello — is that she is very short. (Google says she is 5-foot-3, her publicist says 5-foot-4, my eyeballs estimate she’s maybe 5-foot-2.)

(She is also very beautiful. I remember reading in Amy Poehler’s book, “Yes Please,” that Jessica Simpson was one of the prettiest people Ms. Poehler had seen without makeup, and that tracks.)

Two, she has a warmth to her. It could be the natural nest builder of a 39-year-old mother of three (two daughters, Maxwell Drew, 7, and Birdie Mae, 10 months; one son, Ace Knute, 6); it could be that she spent more than half of her life earning fans and knows how to turn it on; it could be the small-town Texan-ness she wears like a badge of honor; or it could be the fleshy, raw glow of something recently defrosted.

And three, she’s a talker.

You remember Ms. Simpson: a preacher’s daughter from Abilene, Texas, who became a singer, frequently ranked third behind her fellow early-aughts pop stars Britney Spears and Christina Aguilera (“No. 3’s good enough by the way, and I feel that now,” Ms. Simpson told me), married Nick Lachey of 98 Degrees, starred in MTV’s “Newlyweds,” “is this chicken or is this fish?,” Daisy Duke, divorced Nick Lachey, dated John Mayer, “cursed” the “Dallas Cowboys,” billion-dollar fashion mogul, the “mom jeans” that spurred a million headlines about her weight, pregnancy announcements and a new husband, and then poof, gone. She fell out of the everyday spotlight.

Her memoir, “Open Book,” which comes out on Feb. 4, explains what happened through all of it, including the poof.

We made chitchat as we walked toward her cavernous study in the house once made famous by Ozzy Osbourne and his family — she had the flu last week and was feeling better now, but, dang, was it rough; birth order is fascinating; if you want to start your own business, you just … should.

She shuffled there in her fuzzy designer slippers (a woman at ease, but maybe a little tired), and as we sat down I congratulated her on her book, which is surprisingly honest, giving any early ’00s pop culture fan a lot of very, very fun gossip in which to take a long, leisurely bath.

Before I could lob an easy question to break the ice (such as, “Why did you decide to write this book?”), Ms. Simpson began a 120-minute thought journey that was as impossible to lasso as it was impressive to witness.

“Here, world, this is who I am,” she said, mimicking handing over a tome. “This is what I’ve gone through. This is what I was going through in the 10 years that I’ve been silent about my divorce, or anything that anybody had questions about.”

And believe her when she says the book answers any questions you had about her life. It’s over 400 pages.

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Ms. Simpson’s reliance on alcohol to calm her nerves started while she was dating the singer-songwriter John Mayer in 2006. She writes that she felt wholly insecure around him, like she was never smart enough for him, needing pinot grigio or Scotch to help her just frickin’ relax.

Eventually, she writes in her memoir, she knew she had a problem. Having a vodka and flavored Perrier before 7:30 in the morning is not a sign of a healthy relationship with alcohol. But she wasn’t ready to confront it until late 2017 — and that was two and a half years after her doctor told her she needed to stop the drinking and the pills (diet pills among them) immediately because she could die.

She had brief stretches of sobriety before committing fully.

“When I got my liver levels and all that stuff, it was very scary,” she said. “I was very shocked because I didn’t know how much self-destruction I was causing.”

Mr. Mayer comes up in the memoir a lot (a lot, a lot). Ms. Simpson writes that her therapist at one point suggested that Mr. Mayer probably never loved her, he was just obsessed with her.

“Ooh, that broke me in half!” she said of the realization. “And that’s years into being married and having kids. And it was like, ‘Wow. I did this all for obsession? This was his way of loving me?’ I think that it just never clicked until it was just blatantly said to me: That’s not love.”

She didn’t tell him about the book — “I don’t think he’ll be shocked. He knows these stories” — but what if he tries to use this spotlight to his advantage?

“I don’t care.” This is one of the most definitive, and shortest, sentences she said. (The Times contacted representatives for Mr. Mayer, seeking a comment, but they did not respond.)

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Through keeping a journal and then through therapy, and then through writing the book, and then through reading the book aloud for the audio version and writing and recording new songs, which are included for free with the audiobook (they’re O.K.!), Ms. Simpson discovered she had a lot of wounds, not just the Mayer-sized one, that never healed.

“Even though I have been so open about things that I’ve gone through in my life, I’ve never been open about them in an emotional way,” she said. “You know,” and here she started rattling off nightmares like she was listing off what to pack for a vacation, “I’ve been sexually abused, bullied, heartbroken, manipulated,” adding divorce — her parents’ and her own — and her father’s cancer to the mix. (Joe Simpson, 61, is also her former manager; after a remission, his cancer recently returned.)

Ms. Simpson writes that for six years, starting when she was 6 years old, she was sexually abused by a daughter of a family friend (who, Ms. Simpson later finds out, was being molested by an older boy). They shared a bed when the Simpsons visited, which was about three times a year. When Jessica told her parents what was happening, they never returned.

“It took me until I was 13 years old to know that if I wasn’t put in that situation anymore, it could stop,” she said. “That’s why I opened up about it in the book, because I really want people to know at a young age, if they are going through that, just speak up earlier because it could have stopped for me so much earlier.”

Sobriety has helped her start to process it all. “I was like, ‘If this is a crutch that’s keeping me from being my best self,’” she said, referring to alcohol, “‘I have to get rid of it and find what’s keeping me from being myself.’ Why can’t I present myself to the world? Why am I nervous to give myself over to the world when it’s always been so easy?”

“Even with horrible headlines and fat shaming and you name it, I’ve always been comfortable being open.”

(When I told her that Billie Eilish has said she wears baggy clothes so that no one can comment on her body, Ms. Simpson said: “I’m so happy that there’s somebody out there that talks about that and can do that. I think that is why people gravitate toward her. She’s unique and something new and something fresh and something honest to people. Music’s just not the same as it was when I was in it.”)

Ms. Simpson didn’t join a program to treat her alcohol addiction because she “would take care of everybody else first and then forget about why I was even there in the first place.” But she relates to the need for community around sobriety. Her husband of five and a half years, the former N.F.L. player Eric Johnson, stopped drinking the day she did.

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For better or for worse, it has never been Ms. Simpson’s music that has made her dear to us, though songs (and videos) like “I Wanna Love You Forever” and “With You” had their charms.

It’s not her clothing line, either. Well, it’s partly the clothing line. There’s something distinctly inspiring about how quietly successful she has been with it: At one point, the Jessica Simpson Collection cleared $1 billion in sales in a single year, according to the memoir. The business isn’t currently growing, she told me, but that may be because she hasn’t promoted it in a long time.

The last time she did was on “The Ellen DeGeneres Show” in late May of 2017. It’s hard to watch. In her memoir she apologizes to Ms. DeGeneres and to the viewers. She drank before going on-air. It was after this appearance that Ms. Auslander, 39, put together an intervention plan.

She and Ms. Simpson’s best friend, CaCee Cobb, were nervous to confront Ms. Simpson; they thought she would get upset and cut them out of her life.

The four of us, including Ms. Simpson, talked in the in-home recording studio, which is decorated like an Anthropologie dressing room meets VH1’s “Storytellers.”

Ms. Cobb, whom you may remember as Ms. Simpson’s best friend and former assistant on “Newlyweds,” said: “We’ve been together for 20 years, you know what I mean? I know her better than I know anybody. And I knew that would happen out of her defense mechanism, but I was more afraid that if I was cut out and Lauren was, there would be nobody left to take care of her, to get her help.”

Of Ms. Simpson’s drinking, Ms. Cobb, 42, said: “She wasn’t mean, she wasn’t one of those alcoholics that lashed out at people. It was still this” — she motioned to the invisible but very real tether she and Ms. Simpson have between them — “just …”

“Sad,” Ms. Simpson said, completing the sentence.

In early November of 2017, Ms. Cobb sensed that Ms. Simpson was ready to address her problem after a particularly drunk Halloween. The intervention ended up being impromptu, while Ms. Simpson was getting her hair dyed.

“It wasn’t planned that day,” Ms. Cobb said. Things “just got crazy, I saw a window, and it just happened.”

The couple that gets Lasik eye surgery on TV together sees each other, and stays together, no matter what.

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Ms. Simpson has good instincts. They led her to break through the crowded blonde pop star landscape with a reality show; they led her to create a clothing line that her fans could afford (she told me she knows her fans have to save up to buy a pair of boots, so “if you price them at $500, that’s hard”); and they led her to write this book.

Yes, 39 may be a little young to publish a memoir, but her fan base is also about 39 now and frankly, it just feels nice that one of the pop stars from our teendom has delivered on the 20-year-old promise that they’re just like us … only richer and prettier and with great, but maybe not greater, expectations. We still need something to aspire to, I suppose.