I would let it go unless he starts saying stupid shit that can get you into trouble. Then I would go to the cops and tell them he is stalking and get a restraining order.
If you happen to see him around say "hey man hows it goin? I was wondering, What does my cock taste like?" Then just walk away.
Or get him in a dark alley, beat the fuck out of him and get an alabi. Want to come over and drink next weekend? (wink wink hint hint)