How do i get over my ex girlfriend?

me and my ex have been broken up for while now ..we broke up becauseof arugments and drama and now its been 4 months we broke up and i really miss her alot. after we broke up she would just call and we would talk untill oneday she told me im a nobody and a piece of **** to her. we stopped talking and later we started talking back again and then she started acting different and we stopped talking again. now im hearing rumors that shes messing around with other guysand stuff and it hurts me alot because i still love her and want her back but just dont know how to make her realize that im the one she should be with...its like im stressed out and what makes things worst my race car engine went and now i feel as if my worlds crashing down ....i need some advice to get over her. asap!