hi Audrey, sorry to hear about your situation. I agree with the posters here that limiting your time in his family's company is a good idea, if you can't avoid it at all. You can only set a boundary for yourself and if you can't rely on your BF to respond in the way you want, then I'd make plans to do something else if you can for some of the day or just be by yourself. You don't owe your BF to go to his family if they make you feel like this and he doesn't sound like he's treating you in a way that makes him deserve that courtesy.
I hope your Christmas passes by without too much drama.