Cheating MATT LAUER‘s long-suffering wife ANNETTE is headed for more heartache – the Today star’s ex-wife is writing a tell-all book.

Nancy Alspaugh – who was married to the broadcaster from 1982 to 1988 – has lots she can tell…including details of her breakup with the skirt-chasing newsman, say sources.

"Nancy is putting in secrets about her marriage to Matt," a source told The ENQUIRER. "She’s writing a kind of self-help book – about finding your true calling after going through adversity."

With Matt caught in a new cheating scandal and his marriage reportedly in tatters, Nancy confirmed to The ENQUIRER she is writing the book, but insisted she didn’t want to comment on her ex’s recent troubles.

"I don’t want to go there," she said.

But in 2005, Nancy was outspoken when Matt and Annette were having marital problems – a year before Annette filed for divorce and later withdrew the motion.

"I feel sorry for both of them, but if it’s because of his roving eye, it’s very sad," Nancy told The ENQUIRER at the time. "Women throw themselves at him. Show me 10 men who are in the position he is, and I’ll show you nine who are unfaithful – only they don’t get caught, or their wives don’t leave them."

Nancy and Matt first met in Richmond, Va., in 1980 when he anchored "PM Magazine" and she was his producer. They married two years later and divorced in 1988. The couple did not have children.

In 1997, Nancy told The ENQUIRER infidelity was not the reason she had filed for divorce. But an insider told us: "Nancy was very much in love with Matt, but he cheated on her – and she found out."

Fort all the details and to learn about Matt’s cocaine habit pick up the ENQUIRER still on sale!