I did this one, too - my ex- moved into the guest bedroom and essentially would not leave. Only when my prospective partner from DC planned an extended visit did my ex- finally move out.
But then, had he NOT moved into the guest room, I wouldn't have had the impulse to leave town for a long weekend - which is when I MET my partner - so in a twisted way, he actually facilitated the best thing that's ever happened to me.
That's the second time a partner had done something like that - my first partner used me as a free ride to move from Chattanooga to L.A., where he dumped me - exactly where I needed to be ~~~
So maybe, Doug, something amazing will come of it - you just have no way of knowing what it is.
(PS: Don't offer him money to move out - that one backfired on me BIGTIME)