ahh yes. revenge and punishment to someone who hurt us can feel good in the short term. long term i am not sure that it helps that much and can sometimes can make matters worse.
i dont think you should get a gift for someone who you don't want to, but your issue really isn't about the gift, right? it is about his crappy behavior? you want him to be nice to you?
not getting a gift for your AH that hurt you will not change his behavior, make him seek sobriety, turn him nice or make him see the light.
if he is expecting something from you, do you think you should talk w him about not exchanging gifts prior to christmas day, so he is not surprised and a potential explosion occurs?