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Kirstie Alley reveals to ET's Chris Jacobs gritty details of her past cocaine use she thought might take her life and the role Scientology played in freeing her from that addiction.

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"I thought I was going to overdose almost every time," Alley says. "I would snort the coke, then I would sit there, I'd take my pulse [thinking], 'I'm dying, I'm dying, I'm dying.' Who would keep doing it?"

Alley tells Chris that a Scientologist friend prompted the actress to read Dianetics, which the former Cheers star says she sometimes read while snorting cocaine.

"Somehow I got through [the book], and I thought either [Scientology] is the world's biggest scam or I thought this is how I am going to get rid of this hideous compulsion," says Alley.

For more of Alley's interview, tune in to ET tonight, Wednesday, November 7.