When he returns home, just go about your business and don't jump on him the minute he walks in the door. At some point, you will need to sit down w/him and advise him why you weren't comfortable w/him going. Honesty is the best policy and you are in a new relationship w/him. Don't come off sounding like his mother, but point out that you still have some issues w/what he did during his mlcing days and state that it's going to take some time for you to learn to trust him again.
His partying may be one of those traits that he will retain now that he's back at home. Some do retain traits that they acquired during their crisis and others don't.
You can do this...breathe and stay calm.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
