I totally thought i was over it...now it just feels the same as before?

When I was in 5th grade (my last year at my old school) I had friends, was popular, and really liked this guy. In the end of the year I found out he liked me too, but after "graduation" we both went to different schools and I didn't see him for like 3 years. Now I'm in 9th grade, not really any real friends. I saw the guy I liked at our school's Sadie Hawkins dance (yeah I still liked him even after not seeing him for a long time) and tried to say hi to him but I look totally different now and he didn't even recognize me. That was back in September. So for like the rest of that month I was like feeling depressed and stopped eating a lot and stuff. By about the middle of October I was over it, but a few weeks later the feeling that he didn't remember me but I still really really liked him + me really missing my old school and having friends and all, that awful feeling came back, and I felt awful and depressed again. I got over it (again) and middle of November-last week I was feeling great. But today all of a sudden I remembered all that stuff and it made me all depressed again. I thought I was over it this time? Why does this feeling keep coming back? i hate feeling like this but don't know how to completely get over it so this feeling never comes back...I don't like being depressed...