Lou, I don't think you did anything wrong. Please resist the temptation to defend or even discuss with her what you are doing and why. You told her. Leave it at that and stay detached. When she gets down in that mud pit and waves at you to jump in and wrestle (mentally of course ) with her, don't do it. In your avoidance of her, please continue to be cordial-- make sure you're not being pouty or anything. You must keep on the high ground where the grownups are so that it will be clear where any tantrums or unpleasantness originated, kiwm?

If you can let her know that you are not doing this to be mean, but as a personal survival method. To me that should be your focus. "I'm not doing this to punish you. I'm doing this to save myself. I know it's the way you are, but I cannot be around it anymore."

Kind of like when I said to my bf "I cannot be under the same roof with you and alcohol anymore. Not because of what it does to you (which is basically none of my business) but because what it does to me."

I think your strategy shows a lot of integrity. Hang onto that integrity and take care of yourself.

Who knows... a new tunnel may appear and it may have some cheese in it. Heck, she may dig you a new tunnel with cheese when she really gets that the Old Game is over.