Help, Give any idea or advie you have about this....

Hi,
There is a girl in college i love a lot and i can't get her not of my mind. We are both 17. First time I talked to her i gave her a clue that I am interested at her by asking her if a boy ask her out.......blablabla. However before i wanted to ask her out, i wanted to know if she has a boyfriend or not, so i asked one of her friend to find out for me and she said that she has a guy. But i could see any sign of her having a boyfriend. But i decided to leave her alone anyhow and not to think about it anymore. After a few weeks, one of her best mates who i haven't seen in my life chatted to me on facebook. she always chats about her. Once she asked her number form me, once she asked if the girli like is ok. so basically just to shut her up, i told her that i love her(the girl i like) but i let her go coz she got a guy. she said that she hasn't got a guy. a day after she came online again ans said that she just chatted to her and she has a guy. I was like ok no worry just stop this and that's all i want. She still continued. after a week she came online again and said that's she has chatted to her and she has said that she loves me. So I'm confused now and don't know what to do. I see her everyday in college, i can see that her friends always look at me when they see me and so herself....
Any idea, advice or comment about this. Coz im about to get mad...

Sorry for my bad english. I wrote this too quickly...