What's going on here? I Was sleeping with this guy for a while, but now he has a girlfriend. We have tried...

to be just friends, but that hasn't worked out so well for us. He says he loves me and wants to be with me, but his girlfriend just moved here from out of the country to be with him and he doesn't want to hurt her by telling her that he doesn't want to be with her (he is from out of the country also, they are old friends). Last night, we were all at the bar, and I decided that I couldn't be the "other woman" any more (even tho we were sleepin wogether b4 she moved here), so I was dancin and hanging out with one of his friends. He kept givin me nasty looks because I was with someone else, but he was sittin there with his gf too!!! Then, he got up to leave and I followed him outside to ask him why he was mad and to talk about his friend, and his gf gets all pissed off and starts yellin at him. Now, everyone thinks I am the ***** cuz I was messin w/ him when he was w/ her. I don't know what to do... How do I fix this situation??? I like him a lot, but he won't leave her!!!