I don’t want to blurt it out or anything but would that be my best option??

So I was sexually assaulted by my ex bestfriend for about 2 years. I way 1/2 grade in elementary. So 6 I think. And it’s just been something that I feel like they need to know. I have been really frustrated with my self because instead of talking to my family I hold it in and burst at some points. So I just want to tell them so it not on my chest anymore and I want my relationship with my sister to go back to the way it was because now that I keep just letting it out on them my *fake cousin* thinks I’m crazy and need to be put into a mental hospital. And my sister hates me. And Right now we have separate bedrooms but my aunts staying with us for 2 weeks or more and we’re gonna share bedrooms. I just don’t know what to do anymore. I can’t talk to school counselors because they’ll just call the police and I can’t talk to rally any other adult about this because I can’t fully trust them. What should I do.i need a lot of help. Please

*Fake cousin: when someone asks who he is we say cousin but he’s not blood related at ALL

And my sister has gone through a phase of depression and cutting and when my parents found out she got all the attention; so I didn’t want to seem like I was lying to get attention so I just cut and thought about killing my self but never had the courage too. Please I need help.