One of the questions you asked was about communication and spending time together. For men, having you there when he 'needs you' is a comfort blanket. Since he is having a full blown affair, we call that 'having your cake and eating it too'.
He has OW, he has you.
You need to show him that he cannot have both. Not by being mean or nasty but by being unavailable to him. Yes, he's in a mess right now but that doesn't mean he shouldn't be held responsible for his actions.
So, you need to 'detach' from him. Stop spending time with him and tell him that you would "prefer not to do xyz because it only hurts YOU because he is having an affair, and you aren't his 'backup plan'."
When he calls, don't answer the first time. Don't return the call right away. Show him what life will be like without you.
Always be pleasant, or at least neutral. Go get a life and NO MORE sex as long as there is OW in the picture.
Realize that the is NOTHING you can do as long as he has OW. She is a symptom of his current emotional state. In these kinds of situations the WAS often chooses someone who is even more messed up than they are. And it will not last.
