When the LBS is able to take the rose-tinted glasses off and look back at the MR with objectivity, they realize that their partners failed them spectacularly as well and that the fate of the MR is not the sole fault of the LBS.
This can bring up a lot of emotions, and one of them being not wanting to be with that person and wanting a D. As others have said, this is part of the cycle of emotions as soon as the LBS starts finding the ground underneath their feet.
Don't make any rash decisions at this point. You need to give yourself months before you are truly able to take emotion out of the decision.
However, at the point where you are right now, use what you're feeling and translate that into dropping the rope, focusing on your wellbeing, GAL, and not thinking about her. Detachment is layered and you will peel off the layers over time, but it requires consistent work on yourself. Just focus on that.
You will reach clarity about what you want to do about standing for your MR or divorce in time. Don't rush it. You have time - lots of it and exercise patience.
