We were talking in the evening of christmas day about how long kids believe in FC. Long story short MIL then basically with no provocation got stroppy saying if I let my DC too near her she would tell them, and that I was a really bad parent lying to them and deserved to have my children lie and manipulate me. She has since been a total cow and making rude comments about random things ever since.
AIBU to be fuming? DC are quite young so very early on their understanding of the Christmas story, and I don't trust her not to ruin it for our family .