What do I do about this, I haven't actually been happy since the beginning of Summer?

I've gone out with this girl before, but we broke up and I was fine up until sometime last year, when I was in one of her cles, I was happier then too, but now i'm down to the point where shes the only person who can make me smile anymore, and shes with another guy. That's not the whole problem though, I haven't actually been able to have any fun all Summer due to all these rules that make me want to rip all the hair out of my head, what I'm left to do is sit in my room, playing games or thinking about how much fun I had when I was a little kid, which really doesn't help with my situation now. I'm not like the wierd-*** nerdy kid who noone likes, but im still left as the last one picked for any kind of team game, some people try to be nice to me but I just cant bring myself to say much back to them. Sometimes I can't think of anything to say at all to anyone, other times (like now) my brain is racing with things to say to the point of shaking and having a headache. which is also why this might seem a bit mixed up when reading it. I have to walk around all day at school hearing people talk about the fun theyve had everyday, while im sitting there trying my best not to listen, risking a freakout enough to make me rip my locker door off of its hinges and put it through the wall behind me. either way thats all I can think of for now, if anyone needs any clearer form of how im feeling listen to Eminem-Beautiful, that song usually helps me out a bit, also, I probably sound like any other depressed kid on here, not saying im any different from them, but, well... just go by the song and imagine yourself in my shoes, I usually dont when I'm reading these kinds of questions, but when I do, what theyre going through seems a lot clearer, I know ive been going on aimlessly for a while but I cant stop... I just have so many things going through my head right now, that im on the edge of a meltdown, And please dont tell me to just get over it... God I've tried... But knowing what everyone else is doing compared to what im doing, and how I used to be the person people wanted to hang out with all the time, and how now its all gone and left me here begging for help online.. call it sad I dont care, I'll leave here and maybe finish this later when my head clears out a bit, thanks to anyone who tries to help me...