Help, I’m 26 and I’ve never dated, now I'm in an emotional fix

I am 26 and have lived single most of my life. I am currently in my third year of university and have never been in a serious relationship and because of this most people consider me weird but I am happy. However, there is this guy that has been stalking me since childhood and I have always avoided him until he moved into my neighbourhood. I tried to get away from him but two weeks ago, I found myself too weak to resist him and we ended up kissing which I regret. Now his has totally changed and doesn't even greet or talk to me these days which really hurts me because I was starting to have feelings for him. I don't know what to do about him now and I really need your help. Please advise me.