Dean McDermott's Ex writes book

MARY Jo Eustace's life fell apart when her cheating husband dumped her for Tori Spelling three weeks after he met the blond television star - and now she's getting sweet revenge.

A jaw-dropping tell-all being shopped by the 45-year-old Canadian sitcom actress dishes the dirt on Dean McDermott and how he bedded the also-married "So NoTORIous" star only months after he and Eustace adopted a baby girl, Lola.

Her book proposal for "My Husband Left Me for Tori Spelling" begins with McDermott, 38, her actor-husband of 12 years, jetting off to shoot the Lifetime flick "Mind Over Murder" with Spelling, then returning to coldly inform her he'd slept with his co-star and, "We're soul mates. She loves me unconditionally . . . I don't love you any more. And I don't respect you. I haven't for a very long time."

"Wasn't it just two months ago that he'd said he'd never been more in love with me or proud of me?" writes Eustace, who'd moved from Canada to California so McDermott could chase his dreams of stardom. Adding insult to injury, she claims, he got a "Truly, Madly, Deeply, Tori" tattoo on his wrist - but he didn't have money to pay his wife's electric bills.

Still, when Eustace met the adulteress who stole her man, she turned out to be "quite likable . . . [I ended up] feeling sorry for Tori" over what actually lies in store for her and McDermott.

Eustace found herself getting turned on by Tori's soon-to-be-ex, Charlie Shanian. She writes of herself, "Could she one day fall for Charlie? The one man who knows exactly what she's going through?" Her proposal never answers that question.

Book agent Deborah Levine Herman of the Stockbridge, Mass.,-based Jeff Herman Agency, told Page Six's Bill Hoffmann that any woman who's ever been betrayed by a guy will identify with Eustace: "Her story is every woman's worst nightmare. He basically just traded her in."

Eustace, who has a 7-year-old son with McDermott, does take one bitter slap at TV titan Aaron Spelling's daughter, who starred in "Beverly Hills 90210," suggesting Tori is a "has-been" or "never-was."

Last night, Tori and McDermott, who are engaged, fumed in a joint statement: "This is the first we've heard of [the book proposal]. It's opportunistic and undignified that she would want to exploit her former marriage for monetary gain. We only wish her the very best."

pagesix