I am really sorry that this has happened. However, you need - and DESERVE - a man who stands up for you, takes your side, and protects you. It sounds like he has not been doing that, and as much as it hurts now, you may be better off without him.
I went through a lot of the same things with my DH's parents and sister. They were horrible! DH would come to me with things that they said, of course I got defensive. They'd tell him partial truths and do things like not telling him that the reason I got snippy with them was because they were instigating things!
ONE DAY.... He called me at work asking me why I slammed the door in his nephew's face; I said "nope - absolutely not". Ends up, either his sister or her son fabricated some junk about them coming to our house on a Saturday - it never happened. They all tried to cover it up by saying that he knocked on the door, rang the doorbell, and poked his head in the door and hollered in. Baloney - DH, DD, the dog, and I were all at home and no one ever heard anything! Our doorbell works sporadically, but that's the only thing I'll give them. There is NO WAY he opened the door without my knowing because we have an alarm that dings and tells you what door has been opened. Plus, I was working in the end of the house practically all day where that door is located.
Anyway, I absolutely LOVED it and felt totally vindicated (and made a point to tell DH that!!!), and nothing has happened since. So hang in there -- the ex-wife may just hang herself with her own rope!