Oh, Mindybadger!
If you can't handle it any more, then don't. But, what happened to "he has to be the one to leave"? If he's making the decision to end the relationship, why should you compromise on that point? Let him move out and get yourself a roommate. Unless you WANT to pack up and leave town. Maybe whether or not to stay in the relationship is something that is being taken out of your hands, but does your choice of residence have to be? Make sure what you do is what YOU want to do.
If this storm blows over, you might think about couples counseling (or rat poison). It was worse than inconsiderate of him to call and lay this on you at work. It looks like a deliberate attempt at injury and a childish act of retribution. Many relationships do not survive recovery... it's too hard for those couples to adjust to new patterns. But, boy, oh boy, if you ultimately wind up slugging this thing out... you guys need way new patterns. Do you want to continue this?
WAIT! WAIT! I was just kidding about the rat poison!!!!!
You have options. You have explained them to us. Review them. It may help you stop spinning.
Now I just have to add....THE JERK!!!!!
Smoke