My mum-in-law has asked us all to have christmas dinner at hers on christmas day (including my parents). We usually have everybody round to ours, but thought it would be a nice change. However, 6 year old DD did not want to, she likes having everybody in her house (my parents too). So we took her to mum-in-laws this saturday to decorate a tree to help win her round. Mum-in-law is prone to angry outbursts, and was HELL for DH to grow up with, but has been a lot calmer for the last 15 years. On Saturday after tree, which all went well, we sat down to lunch and DD was excited and found it hard to settle, and would not eat soup or sandwichs, but just a biscuit. She then pulled a bowl of tomatoes over and smelt them, where upon Mum-in-law roared "you don't dare put your face in a bowl of food like that!" and slapped her on the back. I gave her a look that could freeze her to her seat, and said "You do not slap her". She said sorry, and admitedly it was a tap, but I don't think DD deserved that, and it isn't MIL's place to do that anyway. DD was very upset, I took her into other room and calmed her down, and we left politely shortly after.
I am now dreading Christmas day! Help - any advice anybody?