At least one person won’t be helping Alanis Morissette’s autobiography sail to the top the best-seller’s list.

The “Ironic” hitmaker is planning to blow the lid off her nearly five year relationship with former boyfriend Ryan Reynolds on the pages of an upcoming tell-all — much to the chagrin of ScarJo, 24, who married 32-year-old Ryan in a private ceremony in Canada last September. Alanis’ book plans could spell trouble for the very discreet Scarlett, who enjoys keeping the intimate details of her personal life off the gossip pages. She couldn’t be more disturbed by Alanis’ plans to tell-all, sources tell The National Enquirer.

Alanis and Ryan began dating in 2002. They dated for two years before becoming engaged. The couple split in 2007, leaving Alanis griefstricken, according to pals.

“Ryan was important part of Alanis’ life, and she plans to dedicate an entire chapter to her relationship with him, how devastated she was by their breakup, and how she felt when he married Scarlett,” an Enquirer spy tattles.

“Ryan will be cool with the book — he’s not especially secretive guy. Scarlett is private, and likes to think that Ryan is hers and hers alone. But there’s nothing she can do about it. Alanis is set on writing her autobiography no matter how Scarlett might feel.”

Alanis was reportedly inspired to pen her lifestory after the recent death of pop icon Michael Jackson.

“She sees how much conflicting information there is about Michael, and she doesn’t want that happen to her,” a friend explains. “She wants to lay her life out for everyone to see — even if it angers Scarlett.”

Alanis has reached an agreement with publishing giant HarperCollins, and will begin working on her memoir with a ghostwriter later this year.