What would really help is to try and stop your stinkin' thinkin'. It isn't doing anyone any favors at all. Especially you. The OW isn't worth rent-free in your head space at all! PPPssssswaw! Not even worth it.
Rome wasn't built in a day. Same with restoring your M. It will be filled with fits and starts. I am not at all surprised at your H's reaction and of course he isn't going all into solution-mode when he is JUST processing the fact that the OW is moving to his office.
If it were me, I'd be shocked too if my own OW had moved to my office. Believe me, I've had my own XOW.
This is a very new wrinkle and it will take some time for you two work through this separately and together. Demanding answers and solutions RIGHT NOW isn't helping the situation at all. As anyone who's reconciled successfully knows, it is filled with fits and starts.
Hey, want a discount on Wonka's Bobcat of patience?! I've got loads of 'em myself.