need advise

Hey you guys this is my first time posting on here! But anyways I need a little help my boyfriend and I have been together for about two years and things are starting to change. It started April of this year when we went to South Carolina, I decided to look through his phone when he was in the shower and long behold him and other girls texting back and fourth when I confronted him about it he "supposedly" told me who they were, apologized and deleted them out of his phone. Well last month I decided to look through it again because he has been acting funny( when people call he goes into the other room. When texting somebody he turns the phone away from me at a angle.. pretty weird things. Thins he's never done before) anyways he has three phones and I only looked through one to see what was up. Well well well here he was entertaining other girls again and when I confronted him about it I was told that since I wasn't paying his phone bill that I shouldn't be looking through it! He never apologized or anything he just keeps bringing up things I have done in the past! Every since that he has been saying im sneaky and doing this and that when I haven't been doing anything. He's been calling me out my name and making it seem like I'm going everything wrong., what should I do?