What should I say to him/handle this?

In the past my boyfriend promised me he wouldn't text his ex unless it was on a wednesday and he had to pay her some money he owed her. Well I decided to give him two chances. First time my friend saw in his cell that he had texted his ex if she had gotten home safely from a drunken night at a party. Today I saw texts from her asking for him to call him back. Its obvious he doesn't want to break the string. We have been dating for a year and a half, and today it made me upset bc we were hanging out drinking and I borrowed his cell to text his bro and accidentally saw the texts from her. He knew I was upset about something but he just left and he projected the blame onto me. Does he care about me and how do I confront him and should I just end it?