That is so devastating. It sounds like you're doing the right things and I'm sure there's still hope. Maybe she wants to end it so she can be with another man but how is she confident it would work out with that man? That sounds like a big risk to throw everything away.
I'm new here as well and don't know what the DB book says about this specific issue (I lost and re-ordered it). What comes to my mind in terms of stalling for time, separate from the DB book, would be to ask her to try x, y, or z first and if those don't work then you'll agree to the divorce but will be working to ensure it's fair. Maybe you can offer the option of waiting six months, going to counseling, or living separately, or something along those lines.
I imagine you could just agree to get divorced and perhaps re-married in the future if she comes back in a year or two begging to try again, and you want to take her back on your terms, but divorces are so expensive.
I hope you'll get some other more useful responses. It sounds like what you're already doing is making a difference so that's good news!
