Roommates mother in law-rant-

So my roommate just got her C-Section scheduled for Monday. I'm so excited for her. 
Her mother in law causes nothing but problems for all of us in the house. Like yesterday she had the nerve to try to put hands on me. 
She's always talking smack about my roommate and myself, claiming that I'm only here to steal my roommates husband when I'm in a happily committed relationship and pregnant myself. Now today she drags my own mother into it saying that she's jealous of the relationship my roommate has with my mother. Well my mother treats her like a human being. And my roommates mom is staying with us until the babies are born. I said this bitch better not be talking about my mom. Talking about me is one thing but don't go talking about my kin. And her mother was like this is all about -roommate- and -other roommate- and those babies right now. Everyone else needs to back off. Now I love my roommate. She's my best friend but her mom is getting on my last nerve. She's been doing nothing but spouting off at the mouth and making me feel like a bad roommate because when I was working she'd have all the house stuff done before I got home and then make it sound like my fiancé and I don't do anything. Before she got her I was cooking dinner every night. And cleaning and helping take care of my roommate. She never wants help with anything. Even though I'm always asking. And now she's going to tell me I need to back off when someone's is talking about MY mother. If it was her daughter or son or any kin she'd have a conniption. But I can't say one commit when this person is talking about my kin. I'm sorry, no, that's not how it works. I will stand up for my kin and if she doesn't like it, she can keep it to herself. I understand that right now the main thing is my roommate and those babies. But I'm pregnant too and I have my own priorities. 
Sorry it's so long. Just needed to rant for a second.