If he ever comes up to you, tell him that you have a wonderful family now and you let go of what was over 10 years ago. If he's that psycho, he should not even be out in society.
You don't have to throw a punch to get him off of you, just show that you've moved on and if someone does not get that they are straight nutty.
Hold a 10 year grudge? A high school grudge? Hopefully he's forgot about high school and see's himself as a grown man, not matter how much of an idiot he is. Word can strike more sometimes, but hopefully he's not a freak and will ignore you.
I agree with Ron Frank.