Is there a way, since she will be staying elsewhere, to see her in very limited doses?
I am not sure about confrontation, per se- is it really necessary? Could the boundaries be stated in a more general way? I think the suggestion to state them as a blanket "Everyone" statement might be less confrontational and perhaps if she feels less singled out, she would actually go along a little more?
(I also live several states away from my mom for much the same reasons. You have definitely got my sympathy/empathy on this.)
I'll be thinking of you and your kids.