You've exposed the affair and now he's in all or nothing and pursuing the OW even more. Been there The best thing I heard to say in this situation is this, "I would prefer you stay and work on our marriage, but you're right this reltionship can't be saved. I'll help you pack up and find another place to stay". You agree with him and don't pressure him to think differently, sort of gently pushing him away in a nice way. Watch what he does next when you show him that "act as if" attitude. If he does move out and closer to her, let him! It's gong to end faster this way if you don't chase him and let it end on it's own
You can try to get support for the bills but I would think he is going to blow you off at first when he's in the A fog. I imagine you could bring it up to him but nothing will get him to change his mind about leaving and supporing both you and the OW aside from spousal support. Depends on his character. If you can try an automatic billing from the joint account.
The best thing I heard to say in this situation is this, "I would prefer you stay and work on our marriage, but you're right this reltionship can't be saved. I'll help you pack up and find another place to stay". You agree with him and don't pressure him to think differently, sort of gently pushing him away in a nice way. Watch what he does next when you show him that "act as if" attitude. If he does move out and closer to her, let him! It's gong to end faster this way if you don't chase him and let it end on it's own