Sounds like the real crazy person in this mix is his ex and not you. I have a friend whose cousin is dealing with an ex like that. He just went to court because she lied to the cops and said he was abusing his daughters. Well, he showed up to court to defend himself and protest the protection order. She didn't even bother to show up. That proved to the judge right there that it was a lie and the order was lifted, all charges dropped, and case closed....

Because you have custody of your own daughter and no history of violence or child abuse, I can't see this going very far.