Kinda need someone to talk to?

So theres this girl and I’ve been going out with her for months and she’s a partyer. She loves to party but shes 19 and im 17 so she go’s to clubs and I cant. She just got some job being a club premoter. She has to go to partys and tell people to go to this other one, I dont know. But I trust her the only thing she did was almost brake up with me for this other guy thats gone in iraq that she met at a party before and she wont stop talking to him. She was like if you dont like it leave me. She says she love me but how can she say things like that. So then I start talking to my ex who left me for my bestt friend and she’s telling me how much she misses me and stuff. So I start talking to her. Not doing anything just talking. Then my girlfriend checks my phone one day and finds out. I told her I wont do it agein and then I stopped. But tthen my ex calls me and calls me and calls me so I pick it up. So we are talking and she tells me to put her number under some one else so I do so we can keep talking. I mean im only talking. Then tonight my girlfriend checks my phone and finds it agein and tells me she never wants to see me agein and how she lost my trustt and stuff. I dont know what to do now.