How to forget someone you like?

Ok, this is sound a bit weird or what. There's someone i like, a girl, in simple, i like, maybe i love her so much. Some details: i don't know much about her and she doesn't know me well too. I meet her when i was in the 10th grade. We barely meet in the 3 years of high school, but somehow i fall in love with her. We almost never meet each other and sometimes we just mail each other. I know that she doesn't want to start a relation with me and hence, she got someone she likes. I've told her i love her, but i think she doesn't take it seriously cause i'm not that kind of man, i'm hopeless in romance and such thing. Now, enough bout the story, i want advice, how can i forgot bout her? cause it driving me crazy, i like her so much but REALITY doesn't allow me to do so. I won't smoke and i don't have enough buck to buy alcohol etc, and i was in the middle of university life. Any good ideas?