It looks like LeAnn Rimes wants to keep the past in the past. There's a new report that says the country star sent a threatening letter to her ex-husband Dean Sheremet after the former dancer dared to refer to her several times in his new cookbook, "Eat Your Heart Out," leaving her none too happy about it.

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According to In Touch Weekly on Wednesday, Shermet--who was married to Rimes before she cheated on him with her current husband, Eddie Cibrian--says that his ex-wife threatened to sue him just because he had written a few details about their failed marriage in his book.

Shermet though for his part is fighting back, criticized his ex-wife for trying to bring him down and threatening to take him to court.

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He told the site, "The lawyers wanted to know what details I included about LeAnn. I just don't get it. She already killed my happiness the first time around. [It's like], 'Move on already, LeAnn. I've moved on!'"

He added, "I worked very hard on this book and I'm proud of it. I'm on people's radar because of my past with her. I can't erase my past; I referred to it and was very respectful. I'm not the one who cheated."

So far Rimes herself hasn't made any public comments about the book.

"Eat Your Heart Out, " a gluten-free, vegan and paleo cookbook, is available on bookshelves now.

Tags: LeAnn Rimes dean shermet