Good stuff here Frank. Your focus and your lawyer's: do everything for the kids. Nothing less. That is all that matters - avoid EVERYTHING else.
Her focus: punish FIB, take kids away.
That will come out in court and may be enough to win the judge over, despite you being not the mom.
My lawyer told me that if I did have to go to trial I would make an excellent witness b/c I was focused. You need to focus now too. Be that parent - out for the kids, not you. Doubt she can do that. It is all about the kids now - not winning or losing between you and her.
Work the schedule Frank. What do you require?? Or better, what do the KIDS require??