Heart Break Problems?

Hi my names darren, and im 15 i must of had about 20-30 girlfriends in the past and they did all hurt alot but nothing quite add's up to what im feeling now. i was seeing a girl for 5 months and she broke up with me because i kept hurting her ... i appoligised and ment it ... she gave me another chance and later that day broke up with me again even tho i didnt do anything that time. she said we need a break and we might get back together but im scared she'll get over me because this girl feels like she was the one for me. idk what to do im ment to stay friends with her but idk how to act around her my brother said be a to her and ignore her so she'll come back but idk if i have the emotional strength to do that. I need advice on how to get her back and not like take prozac and shag lots of girls or something