Wow. Your post reminded me of my situation but rewound back a few months.
My W wanted to move out to find herself at the moment of the "bomb" back in May09. I resisted due to thinking it would allow her to have an unrestricted affair.
After many attempts to break the affair I finally got to the point of saying "to hell with this" and told her she NEEDED to move out if she wasn't going to break contact with the OM.
So W went and got an apartment. Then she suggested we split time at the home with the kids. I said fine under one condition: you have absolutely no contact with the OM. Otherwise you can come to the home to see the kids and/or we negotiate when you can take them.
It might be something for you to try. Tell her she needs to break the affair and agree to zero contact or she moves out. You stay put in the home. Let her have her crazy existence. And don't accommodate any demands or requests unless she busts the affair completely.
Better than having an open relationship, in my opinion.
WAW Using God Me-43 W-40 M-14 S-11 S-9 D-7 EABomb 5/09 Separated 12/09