
four years is a long time, I trust your feelings after that long. if you really feel that way, and it doesn't start to fade after some time meeting new people and having new experiences at school, you should tell him that. but you should give yourself some time to see if that happens, and some space to see if it clears your head. do you have any idea if he still feels similarly about you?
that's a really hard situation to be in, trust me I know how it feels. I think your best move right now would be to try to chill a little (to the best of your abilities), focus on school, make new friends, all that college stuff. if it's been another few months and you miss him exactly as much, you reach out and say hey just so you know, i still feel this way, etc. etc. and give him a chance to respond. there's also the chance that he could reach out to you at any point too.