Harboring resentments all your life just messes with your mind. Stop messing yourself up. You can blame that on the fact that you were abused, and that may be true, but you should still try to get passed it.
But suffice it to say, when I was still a kid and thought about the other kid who almost broke my arm, I was filled with rage as well. I almost never thought about, but when I was reminded I was very angry over it.
But as I got older I got past it. It doesn't make me at all emotional now. The guy and I are not fiends, I still don't even like him, but we're civil and he doesn't push any buttons for me, there are no buttons to be pushed.
That's what I think is growing up and dealing, not simply forgetting.
I respectfully disagree with "most people get over their bullying".
You are emotionally developing throughout your teen years. If most of that emotional development is stunted as a result of consistent bullying, you are going to be affected by that the rest of your life. You'll "get over it" in the way one heals from a serious burn, but there will be scars.
Working in IT, I have met more than a few people with these scars. One individual, when elevated to Manager, turned from being a reasonable person to work with (socially awkward at times), to being one of the most horrible people I have ever known.
Most children of abusive parents still harbor resentment, even if they become healthy enough to move past it in their everyday life. You're expecting someone who was surrounded by an abusive peer group (and an utterly apathetic group of adult "supervisors", who are all but guilty of criminal neglect) not to have negative feelings about his experiences when his former tormenters invite him to a reunion?
I'm not commenting on his decision to not going to the reunion, I'm commenting on the fact that he's still very upset by these events. It's in his interest to let it go, but I don't expect him to be best friends with all his bullies.
In fact, don't ever speak this way to an actual victim of abuse in person, ever. All you'd accomplish is encouraging them to repress their pain and feel guilty over it. People heal in their own time.
Once you do that, I'll give you my opinion. I'm as entitled to do that as anyone.