AITA for refusing to shake the hand of a guy who bullied me in middle school?

I (22M) ran across some people I went to middle school with at a bar, and I was happy to see them. We were catching up for a bit and talking about our new jobs and our college experiences, when a guy who was extraordinarily cruel to me in middle school joined the group (I guess he was running late). I was surprised, because he hadn’t been friends with these people in middle school, but it was a small charter school so I guess they had plenty of classes together in high school. This guy gave me crippling insecurities about my body, my abilities and my overall worth as a person for years, and I’ve only just started to get over them. In fact, a big reason why I transferred schools after the 8th grade was because of him. When he saw me, he said “good to see you man”, and stuck out his hand. I just said “no thanks” and turned away from him. Unfortunately, it got very tense after that, and the conversation died. After a couple more minutes, I said good bye and walked away. Later that night I got a DM from one of the others on social media saying that I was being childish and I made their night awkward. I explained that due to the way he treated me I could not shake his hand in good conscience. They responded with an excuse on his behalf about how he had a bad home life and was just acting out, and I didn’t bother responding because I think that’s completely dodging the blame that he deserves. So, AITA?