Spencer Pratt to Tell All in Book About Soon-to-Be Ex-Wife Heidi Montag

NEW YORK (CBS) Spencer Pratt is planning to share juicy details about his relationship with soon-to-be ex-wife Heidi Montag in a tell-all book.

PICTURES: Heidi Montag and Spencer Pratt

The former "The Hills" star told US magazine that book will also showcase new details about Montag's relationship with her mother, Darlene Egelhoff.

"My last book, 'How to Be Famous,' didn't make the New York Times Best-Seller list because it was in the self-help section," Pratt, 26, told the magazine. "This one is going to be totally different. I'm not holding anything back."

Naturally, Montag wasn't too happy when she heard about Pratt's plan. "This is exactly why I left him," the 23-year-old told TMZ Wednesday. "Right now I'm looking into my legal options."

Back in July, Montag filed for divorce from Pratt after a year of marriage, citing irreconcilable differences. TMZ reported that their divorce will become final on Valentine's Day next year.

Earlier this month, Pratt confessed to People magazine that he chose fame over his wife. "We love each other but I'm a famewhore and I'll never grow out of it."