GIRLS 15-18.... I need some advice...?

I know that it may seem weird, but I've liked this one girl for like 3 years now.... she told me she loved me.... we'd talk on the phone for hours upon hours with each other about the future, and cried to each other about our pasts, and she hinted multiple times that we were going to be together forever, and that we would be going to prom together...we even fell asleep cuddling each other... I believed her, but she had a boyfriend and when she became single, I gave her her space and waited for the right time to ask her out, but she wanted to stay friends... we slowly grew further apart, and I got kicked outta my school for reasons beyond my control. in February, she phoned me and we hung out... it felt awesome to be with her again. she decided to sleep over, and went against her boyfriends wishes... boy was he mad. we didn't do anything though, and I slept on the couch and gave her my bed, because I didn't want to cause any problems. after that, we only talked once more and she wanted me to meet her boyfriend, who she told me about the night she stayed over, and I learnt he is a piece of cr*p, but I had to go out. now she hasn't talked to me since. I really believe that I can treat her better, and think I'm suffering from what they call lovesick or the blues. I really miss her and want her, not as a possession, but as a lover and most importantly, I want my best friend back. Why do you girls do this to the nice guys? Do you not think we have feelings too? And do you have any pointers on how to sort this mess out?