Ok. I realize my last post may have been harsh, and while I still have some questions about your situation, I guess it doesn't matter and ultimately if you're on here asking for help/advice, then you deserve some empathy 🙂
If you are still worried about the past, then here are my thoughts.
Your situation does not sound like this, but let's rule out the worst case scenario. Are you afraid this person is going to physically hurt you or harass you? I think that changes things. I'm going to assume that you don't feel that way, but if he ever got violent or weird or tried to hurt you, obviously report it right away.
Your situation sounds more like he bullied your publicly or mocked you and nobody came to your aide, because you said you had no friends to support you.
If you are really worried bout this, which it sounds like you are, then you have to ask yourself why. It sounds like you recognized you didn't stand up well for yourself and so you have changed that. But did you actually take the time to love yourself and understand that what he said wasn't true? Or...if you believe it was true, learn from those criticisms and understand that rome wasn't built in a day. We take time to change. I hope you also took the time to recognize that the fact that he was mean and bullied you was wrong and that you are entitled to feel bad about it. You need to accept those feelings and move past them. Maybe you thought you did that, but this new turn of events seems to say you are still very bothered and haven't gotten through those feelings. If you can't get past the feelings on your own I think you should talk to someone. Sometimes it just helps to talk and feel validated and sometimes it helps to talk to sort through your feelings. If you went to talk to someone and then you and he had a run in, you would be mentally prepared. Even if that run in was just "hi" and there didn't seem to be any animosity there. Most likely if he's not a total dick, he will feel remorse and will shy away from wanting to talk to you. Or who knows...I do think that it is better to forgive and not forget then hold on to things. I do think it is healthier for you. But, it's easier said than done.
I wish you good luck and if you learned anything from this thread, it's that most of us were/are weird and have felt like an outsider at times.