I don't know if this is in the book and I don't really care. I think you should take the very next opportunity to tell her you don't want a divorce and that you'd really like to try to work things out. Ask her if she'd be willing to put it off for six months, just to make absolutely certain, and if at the end of six months she thought she still wanted to go through with it, then you all can proceed from there.
It's a huge risk for you in terms of potential pain, but... I don't know. If she doesn't know how to back out of it and save face, it might be the solution she's looking for.
