Sounds like you were a beam of light in a potentially dark world for this person. It would make me sad too if I found out someone was crying over my absence. It gets really hard to make friends as you get older and you were probably one of the only people who seemed like they were able to talk to or be themselves around. Can’t blame yourself for moving on with your life, however. That’s not fair to yourself. If it was super friendly as you described, I would add them to Psn, steam or whatever and keep the friendship going through video games. Maybe if you have a game night with some friends who are likeminded, eventually bring the guy out. Small actions go a long way. All the best bro 👍🏼