I've had some bad ones. Sitting in a pub with my mum aged about 11 watching her take her jewellery off, (because I knew that meant when we got home she was getting a beating from my stepdad), taking earrings out meant they didn't get ripped out so damage limitation.
The following few Christmases at my dad's instead, feeling totally unloved watching my sisters unwrap piles of gifts from him and their mum while I got a cheap box of chocolates and a feeling of "we dont want you here, you arent part of our perfect family but we'll tolerate you as it would look bad if we didn't".
But possibly the worst was a few years ago. For the first time in a few years Mum had invited us (me and dc) for Christmas dinner. By this point as an adult my stepdad had mellowed, hadn't hit her for a long time and we generally tolerated each other for her sake. I was looking forward to it, i'd just come out of a horrible relationship (Mum hated him, wouldn't have him in her house). I went round with the dc. Mum was fussing in the kitchen and I shouted through was there anything I could do to help? My stepdad muttered "yes, FUCK OFF". I didn't say a word, made some excuse about nipping back home as i'd forgotten something. Once I got there I decided I was too angry and couldn't trust myself not to say anything so when she called half an hour later I lied and said i'd had one of my IBS attacks and couldn't manage dinner but to carry on and have a nice time with my dc (they were late teens so it wasn't like i'd just dumped them for her to babysit). Unfortunately, one of them told her the real reason i'd gone and she phoned back crying and hysterical. I calmly and nicely just said to carry on without me, I wasn't going to spoil anyone's day by being angry but I couldn't sit there and pretend. I spent that Christmas day by myself lying on the sofa crying. They were all fine after a few drinks so I did the right thing by keeping away. Sadly, I didn't know at the time but i'd never spend Christmas with her again. The next year she was too ill and died shortly afterwards.
I've always made a huge deal out of Christmas with my dc as I had such awful ones as a child and it obviously worked, dd is a celebration monster. Any excuse, easter, halloween, birthdays, she spends HOURS decorating anything in sight and she's an adult now! She loves a good old heap of balloons. Ds is a typical bloke, pretends he doesn't care either way and is happy for his sister to do the work
I'm very glad their memories are better than mine.