Need help speaking out

So I’m 16, I was raped about a month ago. Each day it seems to be getting worse..I cant concentrate anymore I can’t stop thinking about what happened. I keep getting flashbacks and nightmares, I’m crying almost everyday. My grades are dropping. I feel really lonely(among a bunch of other feelings I can’t really comprehend) I’m just sick of feeling this way and dealing with the after affects and anxiety etc. It definitely really affected me mentally obviously and I really want to go to therapy so I can stop living this nightmare. I posted on here a while ago about telling my brother but I chickened out. However I really need help, and I want to go to therapy as I said however I don’t drive yet so I couldn’t be able to go myself. I don’t want to tell a cop, teacher or doctor because I just really wouldn’t feel comfortable enough. I’m a really closed off person, I tend to keep my feelings and thoughts bottled up. I really don’t want to tell my parents either we really don’t have a good relationship my mom would probably tell me it’s my fault🙄😒.. Anyway my older brother and his wife/sister in law are the closest people I have. Now we are very close, like sometimes after school they’ll come pick me up and we’ll all go out to eat or something, or sometimes my sister and law and I go get our nails done together. However as I said before I’m just generally a very shy, keep to myself person, I’m very bad at expressing my emotions and speaking my mind. So I’m very very nervous. Im thinking about telling my sister in law first because to be completely honest I feel a little weird about telling my brother..I want to tell him because he is very involved in my life (meaning, they’re 23 and for some people when their older sibling moves out they kind of like disappear, but my brother like I said picks me up from school often, and we talk on the phone almost everyday...which I also haven’t been doing too much anymore so I think he’s catching on that something is wrong..which is kinda good for me because it encourages me to tell him but anyway..that was definitely way to long of an explanation😬sorry lol) and of course I love him but I mean idk..I guess sex has always been something that kind of makes me uncomfortable, even before this happened not sure why. But I’m also just very modest and so idk..I feel like him knowing that that happened to me makes me a little uncomfortable and nervous, like what if he starts looking at me differently🙁. But anywayy I’m thinking about telling my sister in law first because I think I’ll just feel more comfortable, and then maybe we can tell my brother together. I just really need their support right now. But the grand question this whole post was leading up to is how? How do I tell them😫. Ughh. I’m so scared how they’re going to react too, what if they call my parents, I really don’t want my parents to know. Last time I mentioned righting what happened down on a piece of paper and then giving it to my sister in law and then talking about it after she reads it but idk. What do you guys think? How did you tell someone about what happened?

And sorry this post was so long, but thanks for reading it all if you did.