DP has an ED and I had one a long time ago that's generally managed quite well - his behaviours can be very triggering at times, however. Mine is more orthorexic in nature, whereas his is more AN, with binges followed by extreme restriction.
Instead of just being the things associated with Christmas that are heavy or very calorifically dense, there are lots of fresh fruit, veg and drinks that are light and easily digestible - eating chocolate or biscuits makes me feel sick and miserable, whereas a handful of fresh strawberries and some yoghurt tastes great and is easier on the stomach/blood sugar levels, even before you consider calorific values. DP can either eat the sweet things or, if he starts feeling uncomfortable, he can switch to the 'safe' things I've got.
We've got lots of drinks as well - such as elderflower or Rose Lemonade, as they have a lot of flavour - and plenty of indigestion remedies/herbs/herbal teas to help with any feelings of being overfull or nauseous.
Finally, the meals themselves have lots of 'safe' veggies and we add the things we want as and when we can, using smaller plates and over a longer period - there's no expectation to eat tons all in one short period and then have snacks and sweets more or less constantly in between more massive meals. And there's plenty of storage so that 90% of it can be safely stored in the fridge or freezer until another time, so no guilt about wastage.
I wouldn't feel any guilt about getting rid of additional chocolate and biscuits afterwards. I'm not going to be eating them and DP is welcome to take them into work if he wants, but if they are left here to sit there staring at me go stale, they'll go into the bin.
Another thing I'd suggest is having an escape - if it's getting suffocating, we go out. Even cold and wet fresh air is better than staying inside feeling trapped.
The biggest challenge for us is going to be sitting at the table and actually seeing one another eat. But it's a nice thing to do and we're definitely going to try, even if we end up sitting down in front of the TV not looking or being looked at after the first couple of mouthfuls.
In short, we are taking it as a break from everyday life, to enjoy each other's company, rather than as something with expectations to meet and endure.