Zebra, If gentle nudging works, nudge gently! It's difficult to know if she's kind out of interest in improving your marriage or not, but for now, it doesn't matter. Give her the opportunity to be kind to you regardless of her intentions. If she's going to go through with the divorce in the end, you still haven't lost anything, have you?
Rather than set goals with her as outlined in the book, ask her what I suggest couples ask each other in my seminars- the miracle question. "IF you went to sleep tonight and a miracle happened so that your problems and bad feelings about the marriage disappeared in your sleep, and you woke up tomorrow morning, how would you know watching yourself and me that the miracle had happened in your sleep? What would you/I/we be doing or saying to each other? How would or kids know (if you have them) by watching us that the miracle had happened last night.
If she's not interested in talking about it, drop it. Don't worry about her reading the book. IF you push the issue, it will backfire. If she wants to work on the marriage, she can always read it at a later date.