can i trust him despite his past?

[Sesshomaru_LOVER]

this is a long story and i know its going to sound either cliche or like i am a dumb typical teenage girl but all i am looking for is some sincere advice?
i have been talking to this guy for about his month and i know about his past because he used to date my friends sister and cheated on her with her cousin.
you would think that would be enough of a warning for me but apparently my heart says otherwise -.-
anyways we continued to talk, me being untrustworthy till he convinces me that he is serious and he wants to be serious with me. well we start dating and the day after he asks me out i find out a week later that he had started talking to his ex again about wanting her and thinking about sexual things it nearly broke my heart but noooo me being a derpson decided that he has been hurt before and i should give him the benefit of the doubt and give him a chance. well lately we have not hung out but the last time we did he had logged onto his facebook via my phone which i had forgotten about, and today as i was letting a friend log onto her facebook she noticed something funky and pointed it out to me, upon my checking he had been messaging back and forth with another girl exchanging numbers ad talking about meeting up on today which he told me we could not hang out due to him going to church. should i call him out on it and risk the chance of sounding crazy if they are just friends or just leave it alone and trust him?

[bassspike85]

You already know you're dumb for trusting him, so why are you questioning yourself? He lied to you, several times. Either way the only thing he was serious about in this case was getting into your pants. You know what to do.

[Laro]

Well he told you he was going to church when he was actually going to meet her, thats lying which is enough to call him out on it without risking sounding crazy. I think youve already realized that you should break-up with him but you want someone else to say it for you and thats why youre here. So ill say it, break up with him. You deserve better and this guy sounds like hes not going to change. Youll find someone better in no time