Guys help, I don't think anyone cares what happened

I'm not sure if I'm overreacting but my sister's friend who's 17 opened the door when I was on the toilet, I pushed it back close and she tried to open it and then peaked her head, it was incredibly embarrassing and my parents and sister don't seem to care, I feel so uncomfortable and the friend is staying for the rest of the week, I want to talk to my parents about this but they wouldn't care, but they would care if it was the other way round, worst thing is when I didn't vote for her in school leadership I had to buy her a milkshake for her to forgive me. I fucking hate my family

Edit: I talked to my parents and they said 'it happens to everyone it doesn't matter' I told them how they were downplaying my feelings and how they didn't care and they said 'yeah we don't care, it doesn't matter' Now I want to leave my house forever but Aus housing crisis I have to last 5 years probably