BKS, I just read your current thread, and I would not ask W. I would TELL her. From what I read, she's been controlling and demanding and trying to get under your skin.
Bus drivers get paid regardless where they go. Stop pleading your case - if W bellyaches, say, "I'm sorry you feel that way", grab your kids, and leave. You don't have to be a jerk or rub it in her face, and it's almost guaranteed she'll throw a fit, especially if she's sees she's losing control. But if you do it in the proper manner, she'll soon lose that stance.
I got threats all the time of taking the kids, getting all my money, etc, etc - never panned out, so ignore any of that.