For me, the less said the better. I don't want to be "reminded" of the mess I've gotten myself into, and I don't want someone who really doesn't understand how I'm feeling to tell me how I should feel.
Probably the best thing you can do is to treat him the way you would if none of this drama was happening. If he has responsibilities to meet at home, insist that he meet them. Otherwise, talk about a good book you read, a movie you saw, a news story or whatever. Don't make him and his "situation" the focus of your interactions.