Haven’t had sex since....

So I’m going to try and sum this up. I recently found messages in my bf phone that he was sending his bm. It was him asking for naked pics and wanting to see her and all that. We’ve been arguing for weeks and he swears he didn’t do anything with her. I however don’t really believe it. So we were trying to have an conversation with out arguing. He tells me that we don’t have sex but two times a month and that he wants to have sex with somebody. Now we may not have sex often but that’s because he’s always busy with work and going out of town. So told him if that’s the case he needs to do all that without me. I also told him I don’t even want to have sex with him now especially not unprotected and that I’m going to get back on bc and he got all mad. We were trying to work it out but I just can’t see myself being physical with him anymore. I love this man but I am have major doubts about this relationship. It’s been over a month since I saw the messages. When he touches me I just flinch. I move. I strike up the weirdest conversation to not have to do anything with him. Idc...just I feel strongly that something isn’t right. In the past when I would feel this way I was never wrong. I just don’t know what to do. I have no one to talk to about this...I need help...advice? Something...