So the big day is nearly here... I've been busy planning a naice Christmas eve dinner, as I do every year, for all the family. Just as DH and serve up the turkey with all the trimmings, we notice something is going on between DM and my DS. I ask DM, who by this time has a face like a slapped arse, to cheer up for the DC sake. She disappears upstairs, followed by DS, and they end up having an actual fight (spitting, shoving, headbutting). I am so embarrassed, ashamed and heartbroken. How can people behave like this?