Hi Jeep, I try to follow my thought to its logical conclusion and see where it goes. I am leaning against confrontation. I don't see how it benefits me or my children if you think it thru. My kids know I have changed, they've said it. I do not want to drag their mother through the mud either. I think I will behave well and firmly stand up for my rights.
I would explain your position to your FIL and that's it. Maybe show him the proof but that's it. If she has psychological issues, airing her dirty laundry will not achieve your goal. Is it an ego thing? What is your goal and how does this course of action get you there and at what cost?
