1. He wants to see the baby, he doesn't want to see her, he HAS to see her one last time -- he's being eaten by guilt. Let him stew in it a while longer so it can get a few more big chunks out of him.
2. DON'T contact him, as the others have said. Silence is a powerful thing. It makes you imagine the worst. Especially when you KNOW you've been a complete ass.
3. In times of crisis, you learn who your true friends are. The b@stard who housed WH while you were pregnant? NOT a friend. The people in Europe who accept OW? NOT your friends. The people who REFUSE to socialize with WH because of OW? Friends. The ones who tell him off and then call or email you to say what a jerk he is and that OW looks like 40 miles of bad road? Soul mates.
4. How do you endure the questions when you're with your friends on holiday? Compartmentalize. Stuff the pain in a little box, lock it tight, and tell anyone politely who asks, "I'm not really ready to talk about that right now. What good movies have you seen lately?"
Someone wrote upthread that all BS are handed a sh!t sandwich, but they don't have to eat it. I actually read one I liked better on another thread: WAS are making a sh!t sandwich that they keep trying to get US to eat so they don't have to. Shove it back at them enough, and they have to eat it themselves.
My WFIL has been chomping on his for 25 years. It doesn't taste any better with time...