Huge hugs to @CandyLeBonBon and @Bluntasduck.
Our worst Christmas was probably the one just after my lovely MIL died of pancreatic cancer. She died in the second week of December, and because we needed to give people notice to come to the funeral, and because the church was so busy with pre-Christmas services, the only day we could have her funeral was December 23rd. Dh, DBIL and the dses had to go to the church the night before, and move several Christmas trees (from the village Christmas tree competition) that were displayed in the church. After the funeral, DBIL came back up to Scotland with dh, the dses and me, to spend Christmas.
Christmas was a very quiet day that year, but it did help that we were all together.
The second worst was nowhere near as bad. The dses were still quite small, but ds1 was old enough to tell the time, so we left them a drink and a biscuit downstairs, and told them that they could come up at 7.30am (but NO earlier), if we weren't already downstairs, and wake us up - and then we'd all go to see if Father Christmas had been (we left stockings by the fireplace in the front room).
On Christmas morning, by some miracle, dh and I were still asleep at 7.30am, when the three boys trooped in and ds1 said "Happy Christmas mummy, happy Christmas daddy - and I've been sick THREE TIMES!!" The poor boy didn't realise that being ill was a perfectly acceptable reason to wake your parents early!
He spent the rest of the day in a cycle of vomiting, sleeping, waking up and wanting something to drink, opening some of his presents, and then vomiting again. Dh was doing his best to ride herd on the other two boys, and took them to church, whilst I stayed at home, alternating between nursing ds1, and cooking Christmas dinner. We kept the day going as well as we could, for the other two, but dh was coming down with whatever ds1 had, so he was feeling ropy, and I was busy cooking roast goose with all the trimmings and nursing ds1, so the younger two were able to spend the entire day mainlining all the chocolate they had been given - and when it came time to eat Christmas dinner, ds1 was asleep again, having just thrown up, ds2 and ds3 were full to the gunnels with chocolate, dh didn't feel like eating anything, so the only person who ate any Christmas dinner was me. I'd have been better off saying Sod the cooking and having goose McNuggets!!
We were supposed to be driving over to see my sister and her dh on Boxing day, but dh was too ill to go, so we had to postpone - that was the silver lining, tbh - dsis and her dh were not at all good with small children, and expected them to be seen and not heard, so it was always fun visiting. In fairness to them, the first time we took the boys to visit their new house, ds1 went rolling around on the lawn, and rolled in fox poo, which wasn't his best impression of an angelic child!!