Everything looks good to me except the part about exposing to your wife. I would let HER call me after she finds out that you exposed to his wife and sister, etc..
You need to prepare yourself for her being very angry. She will more than likely be throwing everything she can think of at you and blaming you...
STICK to your guns. Be strong.
"I know I haven't been the perfect husband but you are having an affair, so don't blame me for that. That is totally YOUR doing and I am not apologizing for that."
Throw it right back at her. Be firm. Don't get caught in a long conversation. Cut her off after you say your piece and tell her you have to go. Let her be mad. Stay tough.
