The visible vestiges of Crystal Hefner’s days as a Playboy Playmate are mostly gone. The snowy blond hair that once characterized Ms. Hefner, the third and last wife of Playboy’s founder, Hugh Hefner, has become more dirty blond. Revealing costumes have been traded for sensible clothes like beige cardigans.

But a closer look reveals a woman who is still acclimating to life outside of the infamous Playboy Mansion in Los Angeles, which she left about seven years ago, not long after Mr. Hefner died in 2017.

On a recent afternoon, Ms. Hefner leaned against a pink banquette in an Italian restaurant in Manhattan. She appeared pensive: It had been less than an hour since she had read an excerpt from her new memoir, “Only Say Good Things: Surviving Playboy and Finding Myself,” to a group of strangers for the first time.

Ms. Hefner, 37, said she is still adjusting to life outside the mansion, where she lived for almost a decade and where she “was rewarded for being small.” She’s been trying to shed the conditioning that she endured within its lavish walls. “Coming into power is a work in progress,” she said.

“Only Say Good Things,” which comes out on Jan. 23, is a step toward achieving that power. In the book, Ms. Hefner re-examines her initiation into the Playboy world; details the objectification and misogyny she said she experienced under Mr. Hefner; and mines the trauma that she’s still processing.

“At the time,” she said, “I must’ve been brainwashed or something.”

Ms. Hefner met Mr. Hefner at a 2008 Halloween party at the mansion. The estate offered a glimpse at how the 1 percent lived, she writes in the book, and she wanted to be part of it. Then 21, she was one of many attendees in revealing French maid costumes whom he invited to his bedroom to have group sex as the party wound down.

She soon learned visits to the mansion often involved a “trip to the bedroom at the end of the night,” she writes in her memoir. Back then, she believed it was worth it.

Ms. Hefner moved into the mansion two weeks after the Halloween party, and she started dating Mr. Hefner about two years after they met. (At the time, Mr. Hefner was still married to his second wife, Kimberley Conrad, but the two lived separately.)

As his girlfriend and later as his wife, Ms. Hefner had to routinely maintain her appearance for Mr. Hefner: If she gained any weight, he would tell her to “tone up,” she writes in the book, and if her natural brown hair was showing, he would tell her to make it blonder.

She writes about how she and other girlfriends who lived in the mansion were given a weekly payment of about $1,000 and about how they had a strict curfew that was disguised as a schedule. Breaking it risked Mr. Hefner throwing a fit.

Ms. Hefner said she made several attempts to escape the mansion when she was one of Mr. Hefner’s girlfriends. One time, she succeeded: She told security guards on the property that she needed to buy tampons and went to stay with a friend who lived nearby. But she moved back into the mansion a year later, she said, because she had Stockholm syndrome.

“I just felt like, ‘Oh, this is my destiny. This is where I’m supposed to be,’” she said. “I was 25.”

Ms. Hefner said that she often catered to his desires at the expense of her own because she feared being replaced by someone younger, bubblier, blonder and with “bigger boobs.”

She said those worries were slightly assuaged by their wedding in 2012, when she was 26 and he was 86. (Mr. Hefner’s second marriage, to Ms. Conrad, ended in 2010 after an 11-year separation; his first marriage, to Mildred Williams, whom he met during his college years, ended in a divorce in 1959.)

His union with Ms. Hefner was the kind made for tabloid fodder. Some wrote her off as a “gold digger” and a “dumb blonde,” reducing her to nothing more than another notch in the belt of a man known for dating and marrying younger women.

She didn’t feel comfortable having sex with Mr. Hefner alone, she writes in the book, so she often invited a friend to join them. By 2014, the sex had stopped because of Mr. Hefner’s age and declining health. At home, Ms. Hefner started to become more of a caretaker than a companion: She described herself as “the supportive, loving wife in public” and “the nurse carrying his bedpan at night.”

When he died of cardiac arrest at 91, she at first protected his reputation. She writes about how, before he died, Mr. Hefner made her promise to “only say good things.”

Ms. Hefner’s resolve to keep that promise began fading in 2019, she said, when she started therapy after watching “Finding Neverland,” the documentary that details sexual abuse allegations from two men who had long-running relationships with Michael Jackson.

Looking back at their marriage now, Ms. Hefner said, evokes feelings of regret and disgust. She is still learning how to build healthy relationships and break the codependent tendencies she developed during her relationship with Mr. Hefner.

“When I started dating again, that was hard,” she said, “because with Hef, he just wanted me by him all the time.”

It was only recently, she said with a nervous laugh, that she learned the concept of setting boundaries. “I didn’t have any when I was at the mansion,” she said. “If you wanted to be there, you couldn’t have boundaries.”

Ms. Hefner said Mr. Hefner could be emotionally abusive and some of his other former lovers have made similar accusations. In 2015 Holly Madison, a former girlfriend of Mr. Hefner’s, released a memoir in which she recounted the strict rules she needed to follow at the Playboy Mansion and the ensuing mental health issues she experienced. Many Playmates were upset about the book when it came out, Ms. Hefner said, herself included.

But now? “I see it in a completely different way,” she said.

Before his death Mr. Hefner had denied Ms. Madison’s accusations and others made against him. After Ms. Madison published her book, he said in a statement to People Magazine that he remained friends with many of his ex-girlfriends, but that a few “have chosen to rewrite history in an attempt to stay in the spotlight.”

The PLBY Group, Playboy’s parent company, in recent years has re-addressed the accusations against Mr. Hefner. Ahead of the 2022 premiere of the A&E documentary series “Secrets of Playboy,” the group published an open letter on Medium that acknowledged the “allegations of abhorrent actions by Playboy founder Hugh Hefner and others.”

“We trust and validate women and their stories, and we strongly support the individuals who have come forward to share their experiences,” the letter read. (The PLBY Group did not respond to requests for comment for this story.)

Jennifer Saginor, who wrote a book about her regular visits to Playboy Mansion with her father, a former doctor of Mr. Hefner’s, described Ms. Hefner and other women who lived and spent time there — most of whom were young, thin, blond and white — as “hired props” that helped Mr. Hefner cultivate a certain image.

Ms. Saginor, who became acquainted with Ms. Hefner through their shared connection to the Playboy universe, said she had doubts that Ms. Hefner and Mr. Hefner’s other lovers didn’t know what “they were, like, signing up for” by pursuing relationships with him.

Ms. Hefner said that her life now is a stark departure from her days at the mansion. She buys and sells rental properties for a living and, for the last year, has been traveling between Los Angeles, where she lives, and Hawaii, where she bought a farm.

She’s not sure if Los Angeles is her “forever place,” she said, because she likes the idea of living “somewhere that’s a little less superficial.”