dilemma, gay drama Options

[Persona22]

So, there's this guy that I've been into for the past while, and I've come to the realization that he's been playing me like a frickin harp.

He and I met a long time ago, and from then on it was flirtation and the like, but he's ALWAYS had a boyfriend, and is not capable of staying single for five minutes without getting a new guy.

And, just recently, with his newest boyfriend not knowing, he and I have been hanging out, and getting a little hot and heavy. But then there's the fact that the only time he and I ever hang out is when he wants me to get him some music, a movie, help him with groceries, or some other shit.

And despite him telling me that he wants to date me, he is now in a quasi-cheating-relationship with two guys (a couple no less) totally disregarding me in every way.

Now, what I need help or advice in... is how I'm going to end my friendship with him.
I realize it's not healthy for me to be around him anymore, and have subtly hinted that I want nothing to do with him anymore, but he's never been a bright one.
And then there's dealing with the fact that he and I know the same people, go to the same places, etc... awkwardness.

Help anyone?