There is really only one way to know if someone has changed, and that is to get to know them. Since this is such an emotional situation, and possible dangerous (if he hasnt changed), I would suggest to at least start by going to counseling together. That way she can work through her feeling in a safe environment. And best of all, he would have to reveal himself in front of someone that is trained to spot the tell tale signs of someone who is sexually abusive. This will hurt like hell if it turns out badly, but it will also give her closure and answers either way.