How can I stop being jealous of his ex-girlfriend?

[justmemimi]

I would be jealous, too.
As a girlfriend, though, there's not much you can do... confronting him would probably only make him defensive and he might even say that after all you are not his wife.

There are other ways to make him aware of the situation without seeming like you are too jealous. For example you could frame a picture with you and your cousin (if you happen to have one) and put it where he can see it. Don't explain who's the guy with you on the picture, instead wait until he asks. Assuming that he felt at least a little concerned (don't use the word jealous), this would be the right time to address your concerns, too. He will understand how you feel, because you just made him experience the same. Be creative and use my example to coax him into empathizing with you. Instead of framing a picture, post a picture with you and a guy, too... preferably one with a relative he never met, yet, that way he will feel a bit stupid for feeling "concerned", but it will make him think that if he felt jealous (make sure he utters this word first) about you being on a picture with a relative, then you must feel awfully jealous about the picture with him and his ex on Facebook. You might have to remind him about that picture with him and his ex, though, because some guys just don't connect things in their mind the way we women do. It's very important that you don't miss that crucial moment>... the moment between him realizing that he was jealous for no reason and you making him aware of what you don't feel happy about either. Some guys are really good at changing topics. You have to outsmart him, so you don't seem insecure, okay? Good luck.