So many questions, so little time. As far as when to set your proposal in motion, you suggested two ways of looking at it which means that you have to decided what the usual pattern is - what happens most often, and a 180 would come from that point. I do think it is important to see if she keeps the appointment and gets information. It does help one to see the reality of things. Your comment about telling her that you could not live this way may be perceived as pursuing behavior and a definite no-no. Setting limits/goals is different.
I have another comment about hearing you refer to her as having"fallen out of love with you". Love is a feeling and hence it is changeable. Marriage is a commitment, a decision to be with a person no matter what happens. There are no guarantees about what happens in life, it is a matter of maturity and values and responsibility. Our current world does not support this view. I assume you agree with this thinking or you wouldn't be here and reading Michelle's book.
Have you set goals beyond the separation? I noticed you are to be congratulated for some positive attitudes and 180 comments to your wife. Forget worrying about blame - if you know it isn't your fault - then don't dwell on what she says. I also agree that if she is not with you and bad things happen, she will become clearer about it not being your fault. My H often blamed his poor choices and behavior on me - I was glad to see that when I got out of the way it still happened. Now that he can see that it is his problem he is trying to do something about it. He still blames for everything else but I am sure that will either change with time as he addresses his own issues or it won't be an issue anymore. I let it in one ear and out the other now.