man, I have to be serious. leave this girl alone. this is a good sign. do you want your life partner to be some sort of slut who sleeps around for a £300 I phone. I mean she sold her body for an I phone, how cheap is she. I have two theories for why she is ignoring you, either she knows you heave heard the rumours and she feels so embarrassed and lowly of herself, or she found out you fancy her, and realised all those times you listened to her and was nice to her was to get her on a date rather than being a real platonic friend which is where she wants you. either way take this as a sign and get the f*** out. you are so much more better than this. have some respect for yourself, if a girl can be such a whore you deserve better. find someone nice, someone compatible, who doesn't use you as a girlfriend but is actually really attracted to you, a nice girl who is not going to cheat on you in a few years time for the iphone 2. take this step, don't chase after one crazy whore your whole life who may never love you and will cheat at the drop of the hat. she may have been just using you as a shoulder to cry on all this, as a counsellor for all her emotional baggage. in psychiatry their is a concept known as transferrance, where you listen to the patients terrible stories of sexual abuse etc but you do not allow the patients negative emotons to affect you. the point is all her stories she cries to you about have been affecting you as well. she takes you down with her, and that's what raises her up. stop being used, she gave sex to a guy for an iphone but she won't give it to the nice guy who is so caring and always there for her. wake up, get out, look that bitch in the eye and say"you used me, you silly whore, I have no respect for you, you are out of my life". do this and I promise the next time you look in the mirror, you won't see a boy, but a man. you'll start respecting youself, you'll get more confidence, than the real genuine decent girls will start to be attracted to you. let this whore go. let me know what you do.
this youtube video should teach you the way, link
all the best