Cheating Boyfriends

okay.. so i've been dating this guy for exactly 3 months and a day,
and yesterday i got this message from a girl he knows saying that she was dating him.
i asked him about it, and he said that he wasnt with her, but that he did sleep with her back in October.. *sigh* its not the first time something like this has happened, he cheated on my cousin with me, and then about a month or so after we got together he asked her for the picture of her naked that she'd promised him before they broke up.
she told me, of course, and didnt send it to him.. and he said he hadnt thought.
but i mean.. sleeping with another girl.. thats.. a completely different story.
i dont think i'll be able to fully trust him ever again, and its gonna take a very long time for me to trust him at all now.
what am i supposed to do?
i love him soo much. i mean, you might say 3 months isnt long, but i've had feelings for him long before we offically got together.
ive never loved someone this much, although one has gotten close..
and they broke my heart, but we're still best friends.
but this guy that im with now.. wow.. its so.. powerful and strong.
i just dont know what to do, because im not sure whether or not to believe that hes not dating this other girl.
helppppppp

Judging by the context of what you're saying, I'm going to say that your relationship with him started out with him cheating on another girl. Your cousin.

If he was willing to break ties with her and possibly hurt her while getting with you, why would you be any different to him than your cousin was?

You said he already admitted cheating on you and slept with another girl a month ago.

Take a thorough look at what's going on here. He was with your cousin, and he cheated on her w/you. Now he's w/you. He's admitted he's cheated on you w/another girl who says she's dating him.

Hmm..

My advice is to let this person go as he's not going to change. At least, not because you want him to. He'll change when he is ready and only he can determine that.

Don't let your strong feelings for him be a factor in your decision as he's already willing to break the bond of trust and cheat on you. That was his decision. Let him live w/that.

Hope this helps you out in some way!

I would add that "October" was only 1-1/2 weeks ago. I don't know when the girl contacted you that he was dating her but. . . That doesn't sound too stable. What bothers me is that you don't have anyone you can "trust" since he's done this before and since the girl telling you, she obviously has her own interests at heart and not yours so it's not like either of them are likely to tell you the truth?

The whole mess doesn't not sound promising. I'd move on, as painful as it sounds like it would be.