It's December 22 and most of us are off work/school for the holiday. Our schedules are booked with Christmas parties and gift exchanges and I know as well as you do that eating delicious sweets is a huge part of the Christmas merriment. There's no need to feel guilty about it. Just make a point to add in some extra veggies at your other meals and some extra cardio into your day.
Since you probably won't have time to exercise in the afternoon or evening because of your oh-so-busy schedule, why not get it over with at the start of your day? Wake up 35 minutes earlier than you normally would and get your cardio on! You could go for a run, walk, bike ride, HITT workout, yoga session, swim, etc-- anything to get your metabolism going before you even eat breakfast. This will help your metabolism to be up all day and will counter balance some of those Christmas party calories.
Set your alarm for tomorrow, wake up, and go!