You're only assuming what his response is going to be if you set boundaries. You don't know what his response will be until you do (and hold firm after the initial angry outburst). I know that setting boundaries can really speed situations up (or at least it did for me). But there are certainly cases where the OM/OW doesn't actually want their affair partner to move in or where it will blow up quickly after they do. You never know, your situation could be one of those. If that happens, you'll have momentum in your favor. And if he does move out, it just doesn't seem that much worse than your current situation.
Also firm boundaries force your spouse to treat you nicely when they are in your presence cause you can always tell them to go home or walk away. Of course, all I actually know is that what happened to me wasn't as bad as I was afraid it was going to be (although I definitely took action before considering the consequences since I was trying to regain control of the situation and wasn't expecting her to pick the OM). But I have to think that it hurts a lot more as you spend your sleepless night waiting for him to come home.
Also, if his name is on the lease or the deed, you cannot make him leave without a court order. And he cannot make you do anything during divorce proceedings without a court order and most everyone ends up settling their disputes rather than going to trial. I guarantee you that you are in control of a whole lot more than you think you are and most of the things you're afraid of you don't need to be afraid of.
The nightmare already happened. We just need to learn how to accept it. And both of our situations will come out for the best - we just don't know if the best will include our spouses.
