Should i break up with my girlfriend (kinda long story)?

ok so my gf has quit a past with other guys and other stuff i learned that the past is the past and have gotten over it but have been alot more cautious of what she does well she talks to ALOT of guys which really isnt a problem but she spends time with them more than me she has this thing that she goes to the movies with two other guys and a single girl every week in which one of the guys in in love with her and writes her love letters so i dont like it then she was a ex friend of mine who keot telling people he was gonna get with her and i heard rumor that they made out and he put his arms around her and was walking with her one night well after that itold her i dint want her to talk to this guy anymore and she still does she would go over his house for hours on end and text him send him ims on facebook and all that **** so i looked thru her phone and now she has this auto delte and was hiding the fact she was talking to him still going over his house all that **** after everyone told her he was tell them he was gonna sleep with her and take her from me etc and she still does i delted him from her facebook and she sent him friend request and all this **** plus the guy she goes to the movies with she will go over his house after she gets out of work till 2-4 in the mourning come home and says she tired and go to bed but when its just us she goes to bed around 12:30 1 am but when she with her friends it 4 in the am she had two days off and i spent maybe 2 hours with her she went with her ex boyfriend to the hostpital to see his grandmother then she went i guess then went with him for four hours to his house that hes staying at because it had air conditoner the next day she was gone all day with a guy that my friend told me tried getting with his girl like a year ago and she never asksd me to go with her unless i have an attuide about her going she never calls me to tell me when shes gonna be back or where she at or even if she ok i just think it a little fishy she gets comments like im gonna do what i did last night and crawl into bed with you and she just says ok and i made a fake facebook to she is she was loyal and she told this guy that was me that she would meet him in a hotel and be friends with benefits etc iuts really too long of a story to put here but those are the basic things and i think she cheating and she wander why i told her i dont trust her and she still repaets all of this stuff and thensays sorry when i find out ??? like thats suppose to mean anything to me what do you guys think best answer or advice gets best answer