By this I mean you should just forget about all that stuff that happened between you and your man over the past year and enjoy each other! At the Christmas party or the New Year's bash, don't start any mess. I had a male friend who took a date to a holiday party and all she did was constantly complain about everything! He got so mad he took her home and dropped her off while the car was still moving!
Even if he is the one misbehaving, it's better to just let it slide publicly and wait until you get home to discuss it. You won't solve anything by causing a ruckus, and you certainly won't enjoy the rest of the evening.
You don't want to bring in the new year on a sour note, so do your part to make it a good time. Why do you think everyone is saying "Happy Holidays"? They want it to come true, don't you?