Hormones or justified

So my Sister Inlaw and her boyfriend are 20 and 21. I am 20 and my husband is 23 I have a car of my own and he and I both have jobs. I worked hard for my car and everything I have yes we do still live with his parents Bc we are young and have made some mistakes but my father Inlaw expects us to take my sister Inlaw and her boyfriend who don't have jobs and don't try to have jobs any and everywhere they want to go without compensation. We contribute to household chores we pay rent and we buy food for everyone we are rarely ever home and when we are we stay in our room! Well today she lied to my father inlaw and told him we refuse to take her anywhere when we've taken her multiple places every single day when I pointed that out she wanted to raise her voice at me and try to turn my Inlaws on me should I of just let it go or am I justified in being upset Bc it's my car they put miles on and don't give gas on. Also she wants me to leave her alone with my baby but she's told me multiple times he's a mistake and I should've aborted him. Also she's never had a child and tries to tell me how to raise a baby and constantly puts me down and everyone I love down. Lately it's been so much I have been hospitalized with contractions and signs of preterm labor.