My son doesn't want to go back to school

My son has been in therapy all summer and actually had a good time and I feel has changed for the better. He severely bullied a kid at his school for a few years for no reason besides that this boy was gay. My son used to throw around the word fag and I was always in the office because of homophobic comments he made. No matter how many times I punished him it didn't stop until that boy beat his ass. They fought and my son lost horribly. And he did deserve it. I had later found my sons notebook and I know I shouldn't have but I opened it and it was a lot my son writing his name x the boy he had been bullying. And writing that boys name and hearts around it or my sons name with that boys last name. So he was picking on him because he liked him. I felt this year would be a better year. Therapy went well and my son wanted to apologize and he's been trying to figure out how to apologize to him. I decided to help out and reached out to his mother for us to get the boys together Saturday because my son wanted to apologize and she spoke to her son and said he wasn't really happy about it but he agreed to hear him out. I picked my kid up from school today because at lunch one of his "friends" went into his backpack and pulled out one of his notebooks and they were yelling "Dude! You're in love with so and so!" And starting mocking him and he tried to get it back and they were laughing and the cafeteria was laughing and someone handed the notebook to the boy he used to bully. He said his face just looked a mix between shocked, confused, and embarrassed so my kid hid in the bathroom until I agreed to pick him up and now he's saying his life is over and he can't go back to school. He also doesn't want to do the apology anymore because he doesn't want to face him but I told him he still deserves a proper apology for all he put him through. I get everything is much more dramatic for teenagers but I feel if he apologizes it won't just give that poor boy closure, it will make my son feel better too. Nobody deserves to be outed and I'm sad he was outed but maybe it will help him truly make amends with this person.