I just don't know what to do anymore.Help me, please?

My girlfriend, she and I have had a lot of problems. Things really seem to fixing themselves now..but, just, I don't know anymore. She and I almost broke up last night, because I was threw with the thing's she has been putting me through. Constant stress, forcing me to change who I am, caused me to cut myself out of depression, cause me to stop eating as much. She hits me a lot too, I honestly can not even tell if it is play hitting or what. She says it is play hitting and not abuse, but somehow I feel like she is using this as an excuse.

She never watches her anger with me. For once, I am actually scared to be who I am. Not to mention, she is going to tomorrow nights football game with her Ex-Friend-with-benefits.. I trust her, so when she asked me my opinion, I gave it. I told her that I wasn't comfortable with it in any way. I don't know the guy, and I don't want to. She says that she will not cheat, so I believe her...but I am more scared that this guy, will try to make a move on her. This whole scenario is killing me inside.

She is always touchy feely with a lot of guys..She says she is only playing around and that they are only her friends and nothing more..but I just can not tell anymore..I do not know what to think about this relationship anymore. I am at a decision of whether to tear down the walls and leave or to build them up and stay...Not to mention she is always texting her exes a lot..Please, just give me some advice.

I don't know is it late or not to answer u,and would it be useful,,, but if she do some unacceptable acts for joke then do she by any chance started to put u in some unwanted position with others,,,then what is her real feelings for u this is the question to answer,,, or this is a wish to rule things from her!!
as long as she do that freely act with other boys then u must let it clear for her that u don't like this type of act if she keep on so what level it goes in is it only talk then ignore if more u should care...

but first I see from ur words that words of care sooooooo much some how make ur rules fearing of lose is locking u in,,,I know u care about her but I think its better to have ur own rules that other respect and stay closer then to keep their rules to stay close,,,
u must not c things with the fear she may get sad or leave but that she should respect ur ideas (as u do as I suggest always),,,
A relationship is something each one try the best to let the other feels great and if something is not acceptable they make a conversation to get an agreement for both....
If there is things she ignore to u, and so there is only that fight inside u do she still care or she may go to another one then give her some trust and ignore that all...once she broke anything then without regret cut it off,,,