Hmmm... I detest jealousy. I really do. I don't trust jealous people because I know that jealous people are usually jealous because they have no self-control themselves, and simply assume that everyone else is the same way.
And because I understand focus. Anything you focus on enough usually happens one way or another, so if he's constantly focusing on cheating, it's in both of your energy fields and will attract all kinds of drama into the relationship, the wrong kind of friends, etc. Yuck.
My main rule for being wth someone is that it has to be easy. If they give me a hard time for any reason, other than getting on my case in terms of being my conscious, voice of reason, spiritual mirror, which are all okay and welcome, then I'm gone. If it's not easy it's not love, it's a life lesson, and I've learned a lot and don't care to re-learn Freshman grade life lessons. Jealousy is a freshman grade life lesson and I consider myself a junior most of the time. ;) Obviously I'm not a senior or I wouldn't BE here LOL!
So I hope that helps to answer your question. You're on a downward spiral and it can't help but escalate unless he changes his mindset.