I think its a very very sad story, he has betrayed your trust and ruined what could of been a great life/marriage.

In my head yes he is cheating.

I would personaly insist on marriage guidence and tell him how you want the truth before you can carry on the way you are. Since you know so much you can tell yourself if he is being honest with you, and depending on what he says would tell me if my marriage was worth saving or not.