You knew this was going to happen, so what was your plan for when this occurred? Like I said before, you stayed, that's what he wanted, staying is staying and they see it only one way.
Now that it's time to sign the papers, he won't sign which is as predictable as the tides. So, whatever the plan was for when he didn't sign, do that.
If you don't have a plan, it's time to make one. Whatever the plan is, it needs to be predicated on the idea he won't sign or cooperate.
Good luck,
Cyranoak