I dont usually post here, but I am completely lost with nowhere to turn...

Me and my girlfriend started going out 7 years ago. No kids, no rings, Im 21 she's 22 etc. We've broken up before but all in all i'd say the time we've been together is ATLEAST 4 years. But anyway Monday she told me she was staying at her best friend's house to help her watch her kids (she just had her 4th baby). But then I get called the next day from the girl's sister (who's house she was soposebly staying at untill her bestfriend picked her up) and told me that she left with some guy.. I call her best friend and she is pissed off saying she went to greenville(2 hours away) with some guy and she was so pissed because my g/f ditched her and told me that she doesn't want to be friends with her anymore etc etc. She even told them THAT WE HAD BROKEN UP..

So all last night I was pissed, scared worried. My g/f had slightly MENTIONED spending a little time apart, which I didn't decline, but we talked as if we were just going to work it out. I was even super sweet to her all weekend.We really had no noticable problems in my view.. Well today I got the guy's cell number from her friend. I called and got her on the phone. She was pretty shocked and didn't know what to say, I let her know how I felt.She started half-way crying at one point and said "i told you a needed help" then she flipped the script later and said "i was trying to break up with you the other day" .. I flipped and was like you did not put a good effort in it. Then check this shit out, she was like "nothings going on or anything, I was just trying to make some extra money at the carnival up here"(the guy works there) and that they are at a house with 3 other people and she'll be back in 4 days. Then when I said it was over she acted like that's not what she wanted "can we talk about this blablabla im a stupid bitch blabla" She still sounded upset when I told her i guess she got what she wanted, she replied "i guess so" and i hung up...

Im saddened, very shocked, and not sure what to do.. I really thought she was the one and all signs pointed to her loving me just as much. She's at my house atleast 4 days a week..
Maybe something was wrong and im blind, but I dunno... I guess i'll get on with my life...

I just dont know what to do, I know she's going to try to call me when she gets back to town.. What should I say/do? I guess she's going back to her parents house, I dont know where else she plans to live after this.

PS. She has cheated on me once a couple of years ago when she was drunk. Thought i'd throw that in there.