My spouse cheats. Think he wants to get even with me. He has felt quite insecure.I feel he is mentally sick?

I fear that since he never ever discusses his problems, difficulties or important things about our relationship that he is deliberately avoiding having to face those. He hates it when I get smart, never praises me for anything that I do well. He never introduces me to his friends etc. Even amidst family when we are in a discussion he ties to focus attention away from me. He tries to tell me that I am not that good looking. He has also tried to construct me as angry, inconsiderate wife, mother while his friends (some who know me somehow) believes otherwise.He has carried on with my closest friends and relatives. I know those with evidence. He likes to bring his girl friends home and flirt etc in front of me. I have now left him completely to have his freedom, use it and make decisions for himself through his own learning and experience, what ever it may be. What I realized is that he needs my help, and thought I will try to help him though it takes lots of patience. He has a big inferiority complex, sees faults in all around him and presents them in very subtle forms of dislike and disapproval. He is good looking, and I feel he thinks that's his only weapon. But now that I have gotten cool he is started to be mad at me. If he is ill how ill is he? I feel in this relationship that well I must try and make the best out of it knowing that in any relationship these things could happen and may be it is natural, at least partly. May be I am too inexperienced in this regards. I know he does not want to leave me, and I well don't want to love again and we have big kids.My questions are is it possible my husband is sick? Then what is it? How could I positively handle this?