Leah Remini is promoting her new book about her painful break with the Church of Scientology — Troublemaker: Surviving Hollywood and Scientology — and she’s prepared to spill all the shocking secrets of the controversial church that counts such celebrities as John Travolta, Kirstie Alley and Tom Cruise among its adherents.

Related: Leah Remini Braces For Scientology Backlash With Release Of New Book

In fact, Leah says that it was the way the church treated Cruise that ultimately led to her leaving the church that had been a part of her life since she was a little girl.

“Being critical of Tom Cruise is being critical of Scientology itself… you are evil,”; Remini tells ABC’s Dan Harris in a new clip from her upcoming interview with 20/20.

“As time goes on, you start to lose touch with the real world,”; she says. “The mindset becomes ‘Us against them.’ The decision to leave is you are giving up everything you have ever known and everything you have worked for your whole life.”;

Related: Leah Remini Talks “Repercussions’ Of Leaving Scientology

She adds: “I feel that people need to understand this has been my whole life. I want them to understand how it happens.”;

Leah Remini’s sure-to-be-revealing 20/20 interview airs Friday, Oct. 30.

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