Well, if you can't keep living this way (and I certainly understand why you wouldn't be able to), then it sounds like you have two options.
Possible Option A: Leave. I know that is much easier said than done. If you are having trouble leaving and really think you have an issue with obsession, counseling might help to find out why you are having trouble leaving and give you the courage and confidence to finally do so.
Possible Option B: Stay. If you really want to stay and try to make it work, you could try couples counseling. Perhaps you could get to the root of the issue, find out why he cheats (if he does), maybe spice up your love life, and work on the trust and honesty issues.
