Having Sex

so this is going to be a little long. I'm 17 I was 17 when I started having Sex. I was responsible I used protection now I'm on the pill to be even more safe. I live with my sister in law. she is 23 she realized I had Sex when I asked to get on birth control for the third time. once she told me she wouldn't ask questions if I asked for it. well when I did she's interrogating me to the point where I end up telling her. she starts to judge me for who I did it with. and that happened when they weren't home. they had left me alone for a weekend. I didn't do it at my house or anything . but to this day she judges me for it and makes me feel bad. she started having Sex at 15 and would sneak her bf into the house and stuff . and I don't even do that it was one time. I want the young talk to her about it because it makes me mad she makes me seem like the worst kid because I had sex. she thinks I should tell my brother but I told her no because it's my personal and private life he doesn't need to know about that it's not like I ask about his Sex life. so I don't know how to approach her because she always has to be right and put me down. I want her to stop she bullies me for it. I also forgot to say I've tried telling her I know and understand what I did but she doesn't get it and puts me down. she likes exposing me to her family and they judge me for it. I can't tell her anything cause she gets mad and then I get mad and she threatens to kick me out. she also tries to expose me in front of my brother sometimes. like I know stuff about her that could cause problems between them but I stay quiet but she's pushing me to a limit and I just rather be dead then dealing with her.