mm... Do you really want my opinion?

1. You shouldn't have done it, but you already have. Life goes own. Move on because making more mistakes won't give you any toaster on your birthday.

2. He should be a good father by himself. You can't really decide that.

3. You aren't that guilty after all. His not a kid. His wife should have kept him a little happier by herself as well. If I were married, I would keep my wife so happy with me she wouldn't even think on the possibility of cheating me in her whole life. Get my point? It's always easier to say "he's a s.o.b." than to accept "I've been too stupid".

Good luck.