Judge Says J.Lo's Ex Has to Pay!

Don't mess with Jenny from the block!

TMZ has learned that a judge just awarded the singer/actor nearly $545,000 in a breach-of-contract lawsuit she filed against her first husband, former restaurant manager Ojani Noa, back in April of 2006.

According to the suit, Noa had demanded $5 million from Lopez to keep him from selling a tell-all book about the star. In January of 2005, Noa allegedly sent a letter to Lopez's lawyer, indicating he intended to shop around a book proposal about his ex-wife. Lopez then says Noa wrote a letter saying he'd scrap the book if she paid him $5 million.

The judge also issued a permanent injunction against Noa, barring him from publishing "negative, denigrating and disparaging" details about La Lopez.