Mother in law! help!

My mother in law is so disrespectful and hateful for no reason. I've tried to be nice but she just WONT budge! My husband wants to go see her for Christmas and although I can't stand to be around her or without him I really don't want to go. She's even went to the extent I'm saying my baby isn't his just to be spiteful and evil. Should I go with him to her house for Christmas so I can be with my husband but be miserable around her ? Or should I stay home ?