Well, i did call him. It turns out that he's gotten clean (he was addicted to hydrocodone and klonopin, to my knowledge), and he wanted to ask for my forgiveness, make amends, what have you. We actually had a pretty good conversation -- a little awkward, but not bad. He'd like to hang out with my wife and i, and begin to be friends again.
I'm willing to give it a try. We were friends before we had an intimate relationship, and it's been weird not being friends with him.
So we'll just see what happens.