Please help 😕 all responses appreciated!

All input and opinions are greatly appreciated. I am really really upset. I live with my boyfriend, but have been staying with my mom for the past few days because I've been sick. I was suppose to come back home tonight to his house. His brother and dad lives there as well, but doesn't pay rent. He invited this girl over and has stayed there three days, she has taken my boyfriend's parking spot for three days. She is still there. I found out that she cleaned the house, which is great. I don't mind her being there at all. But Gary told her to use my boyfriend and my bathroom... I was upset, I don't like the idea of a girl using our bathroom, especially when I'm gone. She took a shower and everything without asking. I don't blame her, because Gary hates me and he probably didn't tell her it wasn't his house. I was crying because my boyfriend told Gary nicely that she should use Gary's bathroom instead, and Gary told him that when I come back home he will treat me like shit. I thought it wasn't rude for us to ask her to use his restroom. My boyfriend is mad at me now and ignoring me because I caused this... I don't know what to do. I am 20 weeks pregnant. I don't care if your input is negative, I just need advice. I'm afraid to go back because I don't want Gary to be mean to me...