I don't pick on people now. When I was in school, I was surrounded by people picking on people. It was everywhere. Out of ignorance, I did a little bit of picking (but not much, compared to what I was surrounded by. I am not completely innocent.)
What I wanted more than anything else was a wonderful school atmosphere where everyone liked everyone else and no one picked on anyone. Reality was far from that. I'm idealistic about the world and like the idea of peaceful, happy existence.
Even though I did occasional picking at school, just petty, silly stuff and it was pretty lame and benign because I wasn't good enough with comebacks to be really great at it, I never did anything that was too extreme, like physically fight people.
Me, being an only child, was not used to thinking of endless comebacks to sound witty for the bullies and their cronies.
I was the receiver of the extreme form of bullying from kids who had many brothers and sisters whom they fought with constantly so they were really skilled at being particularly vicious, due to their lifelong experience in these matters.
If one of them apologized to me now, I might be so shocked and surprised, I would be speechless and would probably just walk away. But, I doubt any of these people have the conscience needed to apologize, anyway, or they excuse the behavior as "kids being kids," and they had it much worse at home so who cares?
It's very thoughtful of you to be concerned enough to apologize to this kid. I hope you are able to find him and tell him you apologize for hurting his feelings.