Advice needed

Alright, I need some serious advice. I'm having serious trouble with my bfs mother. She is a nightmare and I honestly think she has bipolar or something..... I might as well add that she dies not speak fluent English and I do not speak fluent Spanish. Today the family was in the room (they all know Spanish fluently) and she was talking to my boyfriend and I asked what she said and she said (nothing, Hannah, I talk to my son". That's just wrong...... she has also treated her daughter like crap when she found out she was pregnant and I've seen her fight with her husband constantly, and yell at her 9 year old son so loudly that the neighbors probably heard. She's said some comments that were not needed and she calls my baby get baby. My blood boils with some of the things she does. I just need advice on how to handle it...... oh, she will point to my son and say that's your son and he is my son. Then she will repeat that he is hers and I don't know what she is trying to accomplish by doing that.....