My husband can be very difficult like this, sometimes, too. He actually has a personality disorder, so that doesn't help. I absolutely know where you are right now. You want to go because you've been planning this for a long time, but he's being (probably--it's hard to tell without more information) a little immature. So now you have to choose whether to go ahead with your plans alone, or spend a tense, unpleasant holiday alone with your husband.
He really should muster up some maturity and go ahead with your plans, but if he doesn't, I suggest setting aside the argument for a few minutes and discuss your Christmas plans as calmly as you can. Tell him your side, that your parents and son have been planning this visit for a long time, and you'd like to go through with it. And tell him that you'd like him to be a part of your holiday celebrations, too. Then ask him how he feels about going. If he just says, "I don't wanna" (which my husband has pulled on me) as him why. If he gives a lame answer, or tries to start fighting with you again, try to stay calm and ask him if there's anything else that's keeping him from going.
After you've given him enough time and listened to his explanation, and he still won't go, ask him what he'd like you to do. Tell him that you feel torn between him and your parents, and are worried that with the argument sitting between you two, that your Christmas may not be a joyful one for either of you or your son.
Try to be open to his suggestions, and tell him how you feel about them. Tell him that you don't want to leave him alone, and that you're really worried that if you go without him, you're afraid he'll use it against you later.
It's hard to know how serious this argument was, but especially if you try to take his feelings into consideration, and you focus on how your parents and son will be affected, maybe you can ease your way through this discussion without another battle ensuing.
Good luck!