A short update to this story can be found here, in the separation/divorce forum:
In short. It's over.
The long and the short of it is that I finally realized what I should have realized a long time ago, that there really was nothing I could say or do that would change her mind. She had made it up long before we ever got to the table.
I probably should have pulled a 180 a long time ago, but that is the benefit of hindsight. I don't know that there was any way I could have reached the point I have reached now without feeling like I tried everything. I'm not so sure that I'm ready to give up, but I know that I have to let her go.
It's horrible and heartbreaking, and I hate that she's forcing us to break up our daughter's home, but I've been sick too long with unjustified hope, and I need to start grieving, and start healing.
I'm not sure how long we'll be living together. It might be until July 1st, but my wife has been having trouble finding apartments, so it might be longer. It could potentially be all summer. I suppose in theory there are a lot of things that could happen between now and then, but the most likely is that we both just become more comfortable with the idea of divorce. I know that I can't see this time as a chance for change because I will just make myself sick again with hope, and then I won't be ready to move on when the time comes.
We are continuing to see our couple's therapist. It is frustrating because our therapy sessions are usually productive. They gave me hope that we could work this out, but now... we might be able to come to a better understanding of each other, but I am 99% certain that nothing is going to change her mind now. This is what she wants.
I'm not sure how I'm coping at the moment. It's the same horrible pain most of the time, but a part of me feels like the burden has lifted somewhat. There is a strange liberation in giving up. Still, there are triggers everywhere, and the slightest reminder, the slightest memory can send me into a spiral. I think that I'm going to be very fragile for a long time.