Cigatettes, drugs and alcohol?

Well basically I'm in college and lifes becoming ****, in year 11 I went to endless parties, and now well I have a group of friends and it's the best friends i've ever had, well they fall out and **** happens, i hate it and love it at the same time. Drugs, smoking and alcohol make things worse, we have parties and drink and do drugs (only weed) but this piles on and makes me feel worse, I just think a spliff now and then if you and a mate are bored on a field is a way to p the time. I have a friend that looks down on me, well it seems that way, and he has a girlfriend, which I kind of like, i ****** up right?... well basicially we went to this party and sold a **** load of drugs. but lifes just getting ****, and we're all in college, a typical college life, what should I do? I dont know the answer myself :/