ESH

I'm not from America. About 30% of my country's population are vegetarians so the idea of me ringing up vegetarian friend and insisting I bring a meat dish to their household is just so mind bogglingly rude to me. So poor form on your SIL/MIL.

Your husband should be leading in building a bridge here but you have backed him into a corner.

However, the mature thing to do would have been to tell your husband and his family that since having turkey/meat is so important to them that you cannot host it. Or have sent them a menu beforehand showing them your good faith effort to give them a feast without compromising your beliefs. Instead you've escalated.

I don't think you should sit out Xmas. Go and make amends and try to understand each other. You've married into this family, you and your husband need to figure out how to build a relationship with them.