I was struck by the above; if you tell someone else something important to you, they should pick up on that and "care", either in a very supportive way or it should bother them, or they should. . .something. If you can't tell, if they just "didn't seem", then it would strike me as their not paying very good attention to me. A quick, "No, that's all right, babe" or similar would not do it for me. I would be surprised if something difficult for me were that easy for the other person.

Now on to do I think you should give him another chance. . .

If I were in your shoes; that you were suspicious, went looking, and found; I would not like any of those three verbs in my relationship? I would fall back, regroup, and work on my own self esteem and learning better communication skills; not necessarily just for one's own "use" but so you could spot a person who is bad at it and not associate with them.

If you have a PhD you don't generally associate with high school drop outs; not because there is anything wrong with high school drop outs, just that they are not very likely to have much in common with one. Yes, one "could" perhaps make it work but the problems the differences cause make it something just "love" can't quite be enough for.

Maturity is similar; I think that is why you don't see as many older women with younger men; older men who decide to drop their wives and date younger women, in my opinion, tend to be less emotionally mature than older women.

To me, maturity seems to go hand-in-hand with self esteem; I would work on my self esteem and communication skills (so you don't have to go looking and find, you know how to communicate what you want to know and judge the answer) and jealousy doesn't occur to you because of your self esteem. I'm not saying you will never be cheated on again, just that you will have a lot more tools to both dodge more bullets and fire off a few of your own if endangered.