After reading your situation, I feel that if I were in your shoes with no kids, Wow! I would leave him when he least expected it.
Here's my story:
I felt that my H may be in a little flirting with a female co-worker or the female flirting with my H. Oh well. One night after an argument with my H earlier in the day, I passed by H's friends house when i saw that his car was there. I saw a females shoe by the front door, of my H's friends house (she was the only female in the house with five other guys), I stopped by unannounced and started yelling at my H, and yelled her name out to come out (so I can see who she is and let her know who I was). Well, I told her that you are the reason me and my H argued earlier today because you were at a party and sitting next to my H the whole time last night. I asked her bluntly, do you have something going on with my H? She said no, I am here because I was invited by Jack to come over. Yeah right what a coincidence you're in the same house with my H. Anyway, before I left, I DID apologize to the owner of the house for my loud mouth and he said, I am sorry I am the one who invited her over, H did not tell me, if I had known I would not called her to come over. He apologized, but I feel there maybe some cover up. Who knows!?
Well, so the bottom line was I exposed him, her, to the other people there, and his supervisors are aware of the incident. I am not one bit ashamed of it because I know that I had to do it to show that I will not allow that kind of bull**** to happen. We went through so many trials before and he wouldn't be where he is now if it wasn't for me supporting him all that time.
So, he knows better now otherwise it will be a large child support. He knows I got my eyes on him, if not, I will hear about it sooner or later.
Bottom Line: Expose him! He might realize his selfish actions.