I want to break up with my girlfriend...?

Ok so me and and my girlfriend have been together 2 years(ish) and i THINK i want to end it with her. I went away to uni and found out she cheated on me and i forgave her but we still broke up i ended up going home and spending time with her again and we just fell back into a relationship. But now shes going all crazy keeping tabs on me and just having a moan about everything i do. Not to mention she hates like everyone of my friends who i am extremely close too, and won't let me have friends who are female who i met through her and get along with well I love her or at least think i do, shes my first real relationship after years of sleeping around and not to mention she suffered with bulimia and if i end it with her im scared she'll resort to that again.