Actress Jessica Joan was part of the NXIVM cult. Then, she helped expose it.

• Actress Jessica Joan has written a book about her life inside the NXIVM sex cult.
• The model, once part of NXIVM's secret "DOS" group, later helped bring down leader, Keith Raniere.
• "The Untouchable Jessica Joan: A Real Life Journey Of Love, Forgiveness And Evolution From The Jane Doe Who Helped Bring The NXIVM Cult To Justice" is out now.

For nearly four years, the actress Jessica Joan has stayed silent about her involvement with the NXIVM cult and her work to help dismantle it prosecute its leaders.

Even when she started talking to the FBI, she kept her identity private. In court documents, she was known as "Jay."

Now, in a new book, "The Untouchable Jessica Joan," she writes about what led her to join NXIVM and how she was able to escape. In an interview with Insider, she talked about her own healing and finding the courage to speak up.

"For me, sharing my traumas is a type of way to overcome them. I want to show the world you can come out smiling," Joan said. "You can come out winning and take down the bad guy."

It all began when Joan was working as an actress in Los Angeles and growing tired of the shallow nature of the Hollywood scene. She wanted more, she said. Something more meaningful.

One of her best friends told her about a course that was becoming popular in their circle. It was called ESP, which stood for Executive Success Program, and it was was part of an organization called NXIVM. Joan ended up at a presentation where ESP coaches talked about helping people reach their highest human potential.

NXIVM was really skilled at marketing- they attracted good looking and successful people, like Allison Mack of "Smallville" and Kristin Kr euk of "Beauty and the Beast."

That's when Joan thought, "What's the worst that can happen? What if this is something that can really help me?"

She paid around $3,000 to enroll in an intensive ESP program.

When Keith Raniere co-founded NXIVM in 1998, it was marketed as an "Executive Success Program" for personal and professional growth. It hosted development seminars and had different subgroups, including "The Source" for artists and performers, "Society of Protectors" for men, and "Jness" for women.

But behind the scenes, they were also recruiting for a secret sorority called DOS, or The Vow, which was run by Mack and where members were coerced and blackmailed into being sex slaves.

After The New York Times published an expose in 2017, more of NXIVM's victims began speaking out. The next year, Raniere and Mack arrested in Mexico. Raniere is now serving 120 years in prison for sex trafficking, racketeering, fraud and conspiracy charges. Mack, who cooperated with prosecutors, got a three-year sentence.

But before discovering NXIVM's dark underbelly, Joan, who has spoken before about enduring a traumatic childhood, saw the group as a positive force in her life.

"It was something full of light. It was people who had gone through traumatic experiences that wanted to heal themselves and also wanted to help other people heal and help humanity," she said.

After three years with ESP, its members had become her "best friends and some of the closest people in my life."

It was then that she was invited to join DOS, which Mack insisted was a women's empowerment initiative.

Joan would have a "master" and even a "grandmaster" - Mack. But it still seemed innocent enough, "like how in karate, you have your 'master'' and in yoga, you have your 'guru,'" she was told.

From there, it only got weirder. Members were required to send collateral - anything from pictures, secrets, or anything that could be damaging to their friends or family - in order to remain part of The Vow. They were also forced to count and limit their calorie intake, and report everything they did to their "master."

Privately, though, Joan had her own collateral: she kept pictures of everything she turned over. "I had all this collateral and evidence saved in case anything happened," she said.

A Lucky Escape

As part of an initiation, members were required to attend a "special" ceremony where Raniere and Mack's initials would be branded on their pelvic area.

But Joan wasn't able to attend the ceremony because, she told the group, she had to travel home to see her sick grandmother. This earned her a hostile reception, she said. In the end, Joan says, she was never branded, and she never had sex with Raniere.

"If I had gone through with the ceremony, I know I wouldn't be able to stand here in front of you today," Joan said. "And to think I'm one of the lucky ones, I don't have to walk around with a permanent brand on my pelvic region."

When she did leave, she began talking to the FBI. She spent the next three years working as a model and waitress all while flying back and forth from Los Angeles to New York to give information to the authorities about NXIVM. She would eventually serve as a key witness at Raniere's trial.

"I felt like I was on a mission," she said. "Because, I didn't have to testify. I didn't have to do any of these things and risk so much."

This summer, Joan spent the last of her unemployment check to attend Mack's June 30 sentencing. But she said she was surprised and angered at what she saw as a too-lenient sentence of three years in jail for sex trafficking.

Still, she doesn't regret her cooperation with the authorities and says that, having found her mission and taken the time to heal, she wants to use her story to empower others.