Monster in Law from hell?

I swear I have a monster for a mother in law. I just recently had a miscarriage and I am in deep grieving. Work gave me 2 days and if I need to 3 to get over this. Well she wanted to hang out with me and my sister in laws which seemed okay to me in the beginning. Then on the way home she rode with me. I told her that I wanted to go home and she went nuts after that. She started saying that I never want to be with her and that I push people away and the worse one was she told me I never was pregnant and that she refuses to believe that her son lost a baby. That did it for me. I was crying and I was the one driving. She told me to pull over into a Kangaroo gas station so that my other sister in laws could pick her up. She even went as far as to call my husband and tell him that she doesn't believe she lost a grandbaby when in fact she did. My husband will not stand up to her. Everytime I am in the car with her she brings up finances with me and makes me upset. And now this happened and I honestly don't think I want to see her at all anymore. I don't know what to do. Can anyone help?