I'm sorry you had to go through that. I'm glad it wasn't me - cuz lately (maybe it's pre-menopause or SOMETHING) I've been pretty vocal and would have called her on it and say "Excuse me? What did you say?"
My teenage son was practicing his driving this weekend, when a bunch of the neighbor kids yelled to him "GET OFF THE ROAD, LEARN TO DRIVE!" We stopped and I yelled "Excuse me? What did you say?" - they all got quiet and one kid said "nothing". Funny how they had nothing to say...
