Martha Stewart had a meltdown after finding out that her darkest, deepest secrets will be exposed in a tell-all book written by her former best friend!

The explosive memoir by Mariana Pasternak will reveal intimate details of 68-year-old Martha’s private life, including her lesbian "dates," the attacks she faced in prison, and her boozy temper tantrums, sources tell The ENQUIRER.

And the domestic diva is worried sick that Mariana will reveal she cheated on her ex-fiance Charles Simonyi, according to insiders familiar with Mariana’s book, The Best of Friends: Martha and Me due out in March.

"Martha has good reason to be panicked about the book. Mariana knows everything!" a former colleague of Martha’s who was also close to Mariana told The ENQUIRER.

"Martha has called Mariana in tears, screaming at her, ‘Why would you do this to me?’ She still doesn’t know exactly what Mariana has written, but Mariana knows Martha’s most intimate secrets, and the book is sure to spill them.

"Martha is under extreme pressure from worrying about which secrets the book will reveal. She collapsed in tears in her bed wondering how badly her reputation will be affected."

Martha and Mariana, 56, were close for more than 20 years. They chatted on the phone nearly every day, lived around the corner from each other in swanky Westport, Conn., and took vacations together.

But in 2004, Mariana testified against Martha during her stock trade trial, and her statements helped prosecutors win a conviction. Martha eventually served time in a federal prison, and she never forgave her former best friend, insiders say.

"Martha considered Mariana a turncoat, someone who said whatever the prosecutors wanted," the pal divulged.

"Now Martha feels Mariana has betrayed her a second time by writing this book."

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