Help! Mother in law stress

I am 21 weeks pregnant and I am easily stressed out person. My family and my husband, along with my coworkers have been doing a phenomenal job of keeping me calm. My mother in law on the other hand I find extremely stressful. She has been picking fights with my sister and mother along with myself. I come from a large Italian family and let me tell you my family has been putting her in her place. The tension is really starting to get to me and thankfully my husband is on my side.  I decided that the next couple of months I try to avoid her as much as I can as to not stress the baby and myself out. Any advice would help!