You will be back on routine by Jan. 2. Just keep reminding yourself that there is an end date.
So with that in mind...you might as well give in to this a little bit. If you come home to a messy kitchen, tell him he needs to either clean it now or cook dinner for your family/order take-out.
And then relax and enjoy the take-out!
Since it's only for a few days, you can do this. Pour a tipple too much wine in your glass if that is what it takes.
What is the worst that can happen? A mess. You have time to clean it up/get help cleaning it up.
Do not let yourself be chained to his parents. Spend part of the day with them, then run some errands. Take a long walk or run by yourself. Invent movie plans with a friend, if you have to. Hell, see a movie by yourself!
You do NOT have to sit around staring at each other to be spending holiday time together. Get thee out of the house!