Well, I actually moved him out of the room to set a boundary when he resumed contact with OW after telling me it was cut off. But I suppose I could say, "it stopped being 'our room' when you chose to resume contact". Although, that would immediately start a fight. I just didn't respond at all when he said that.
You can end that fight by pointing out that you will not stop him from making his own choices, but he has to live with the results.
If he resumes contact, then he's not sleeping in the same bed with you. That's a boundary.
Me: 44, Wife: 39 M: 17 years T: 20 years Bomb on 08/25/09 1/13/10: MC started 1/28/10, 2/8/10: More bombs 8/28/10: Wife moved out No talk of D, no movement