My girlfriend is way too attached?

I have been dating my girlfriend for two years now. We did break up for a while but we got back together. it seems like there have always been problems between us for instance i would make a mistake and i would bet BI***ED at for it an unnecessary amount and this seems to happen allot and i tend to do nothing but take the harment. The only time i do end up sticking up for myself is when i just cant take it anymore and i will eventually tell her to stop with being such a psycho. Although it seems like she thinks im basically worthless she is getting scary attached to me. I no longer have any time to my self. If i say i want to go do homework alone she will get mad at me and i have to force her away. but what really concerns me is that a few days ago she wanted me to sleep over ( I have slept over the past week) and i told her i want to just sleep in my own house that night because i had to get up for cl at 630 (she knows i am a very light sleeper and need my space to be comfortable) and that is when she started balling her eyes out at me. telling me that she needs me there and if i left it would be bad for our relationship. I eventually got so upset and confused with her that i had to leave. I don't understand how anyone can be that obsessed with me after treating me so harshly all the time. She also hates when i go to spend time with anyone of my friends and she gets jealous if i talk to any girl that isn't one of her close friends. I really don't know what to do here