I understand he is emotionally dependent on you for his own reasons, what are you going to get out of this relationship? Guilt? It seems that his wife does not have respect for him as she is least bothered about reasons for his infidelity but must be insecure on financial ground. He might not be taking proper care of their financial needs for whatever reasons. I do not think that you can make him realize anything about which he is not serious (as he is not sure about his wife, whether she is good or bad). He has found you as a support and he does not want to lose that, only you have to decide how far you go on doing this because his problems and needs are going to be never-ending stuff.