I would stay friends with him, but move out of the relationship. I had a similar situation in a past relationship. At the time I tried to forgive him, but I constantly found myself harking back to what he'd done. In the end we broke up, and although I'm now on friendly terms with him, I'm very glad that the romance broke down. He's gone on to treat his second wife even worse than he treated me, and is now on his third long term relationship. Some men just don't know what they have when they have it. It might be better for him to learn early that you can't mess about like that. If you can teach him one lesson that's a good one, it might even make him happier in the long run, as well as you.

But it's difficult, I know. Perhaps he's just young and foolish, and he won't do it again. You know him better than we do.