Should I hold on to him?

I've been crazy about this guy for the longest time. I've even written like 15 songs on this feeling. I was really confused since the beginning. There would be these small things he does that makes me wonder if he felt the same. Things like asking me if I would wanna go with him and his friends when they'd wanna hang out, but then he doesn't ask my friend. Just me. And to think she was right in front of us. This happened one other time with the same people. I was on the phone with my friend and she was talking to him online (note that I didn't have any net connection then) then she ended up typing in for me. We ended up making her an invisible secretary. Then one day, I found out that I needed to move half way around the world. So I knew I had to tell him. When I confessed, he didn't say anything that would tell me if he felt the same. Then I moved, and found out he liked some other girl. I was sad, but more on why he didn't just tell me he didn't feel the same right then and there. I know it's hard to tell that to someone, but it's hard for me too to hang on to something useless. We promised to see each other again in a few years, and I can't help but wonder what it's going to be like then. I know it's more than just a crush. There are so many WHAT IFs and MAYBEs going through my mind. What if he just gave up on the idea of liking me because he knew I was going away? Maybe he just thought it would just make things difficult and decided it was best for me to move on. I really don't know. Do you think I should just let go off him? Or do you think I should keep these feelings locked up in my heart, then when that day comes, when we meet again, see what happens? I really need some kind of help.