I know first hand that talking to MIL is not a good idea. Stop talking to her about W. Your W will only be pissed off more at you. I am not sure how far along you are in your journey but I made the mistake of talking to her family early on in my process. Her family are her "people" to discuss problems.
Respect that she need support from her family.
I have an excellent relationship with her familyso I know it's hard to not ask questions about her mindset.
You are in a good place for what your about to endure.
Patience, take care of yourself first. Do some soul searching about yourself and think about what it has been like living with you from your W's POV. MAke your changes for yourself. Keep us posted.
Bomb 8/09. Brief piecing 12/10. D-2/12 Two incredible kids D9,S6 Leading new life! “Success is not to be pursued; it is to be attracted by the person we become."