Maureen McCormick Book Details Drug Use

reveals details of her downward spiral into depression and drug addiction --even trading sex for drugs, in her new tell-all, "Here's the Story: Surviving Marcia Brady and Finding My True Voice."

McCormick, who played Marcia Brady on The Brady Bunch from 1969-1974, also writes about her relationships with Michael Jackson and Steve Martin, and chronicles her affair with "brother" Greg Brady, played by Barry Williams.

"We couldn't hold back any longer," McCormick, now 52, writes in the book. "It was our first kiss, and it was long, passionate and deep. It was wonderful, too, though as we continued to kiss and press against each other so closely that we could feel each other's body heat, a part of me — a tiny part, admittedly — said to myself, `Oh my God! I'm kissing my brother. What am I doing?'"

After the show ended, McCormick, who grew up in an abusive family, had a hard time reconciling her real life with the one on TV, and began a drug-fueled downward spiral into depression.

"As a teenager, I had no idea that few people are everything they present to the outside world," McCormick writes. "Yet there I was, hiding the reality of my life behind the unreal perfection of Marcia Brady."

McCormick turned to drugs, using cocaine and Quaaludes, among others. She struggled to regain some of her previous success, but was hindered by a reputation of unreliability due to the drug addiction, even blowing an interview with Steven Speilberg because she was high.

She details cocaine binges and parties at the Playboy mansion and at the home of Sammy Davis. Jr, trading sex for drugs, and an unwanted pregnancy.

Marcia, Marcia, Marcia. (It had to be said)

The book hits shelves on Tuesday.