A former NXIVM cult member is speaking candidly about her ordeal.

Sarah Edmondson, 42, spent 12 years in the cult led by the charismatic Keith Raniere. She said she was selected to join a secret sisterhood within NXIVM and as part of the initiation she had "KR" — Raniere's initials — branded into her skin.

"It was horrific," she told Inside Edition. "The whole point was to experience pain and to overcome the pain, to be really strong, so they cut our flesh open without anesthetic."

The process, she said, took 20 to 30 minutes. "Some people, it took 45 minutes," Edmondson said, explaining that it wasn't a stamp, like cattle.

But far from being the personal growth guru he claimed to be, Raniere was actually preying on some of his disciples for sex.

"It was a betrayal of the deepest level ... to find out that everything that you've been fighting for, or advocating for, or vouching for, is not only bad but it's the complete opposite of what you thought," she said of the moment she realized she was actually part of a cult.

She added: "My whole life got ripped out from underneath me. It was incredibly traumatic."

Edmondson opens up about her experience in "Scarred: The True Story of How I Escaped NXIVM, the Cult that Bound My Life," which was published Tuesday.

Another member of the cult was "Dynasty" star Catherine Oxenberg's daughter India. She finally broke free last year following Raniere's arrest.

"She is moving on with her life," Catherine told Inside Edition in 2018. "It is a complex situation, but she understands her mom’s struggle, and the people involved. She is doing really well."

Catherine is now the executive producer of the new Lifetime TV movie "Escaping the NXIVM Cult: A Mother's Fight to Save Her Daughter." She hopes that it will draw attention to cults that prey on victims.

"If I can help other families avoid going through the pain my family went through, that makes it worthwhile," she told Inside Edition.

Raniere was convicted of racketeering and sex trafficking. He'll be sentenced in January and faces up to a possible sentence of life in prison.

"Escaping the NXIVM Cult: A Mother's Fight to Save Her Daughter" premieres Sept. 21 at 8 p.m. on Lifetime.

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