Stress overload

So I'm going through a really stressful time right now. My sister has lied about a lot of stuff, things as serious as abuse. She is now in a facility to try to figure out what all is going on. Last week she was diagnosed with 2 different mental illness. I don't remember what they are.
​But I'm 14, and I'm stressed about it, I'm also mad at my sister for telling so many lies. I'm upset, and just generally not too great. 
​I broke down after English today in school, because of all of it. I feel bad for my English teacher, since he was clueless. 
​The point of all of this is to say, I need some help. I need some new ways to deal with all this, since usually I dance, and sing, but that isn't enough right now. I also write stories, but I haven't been able to do that, so... I don't know what to do, and I'm tired of everyone saying it will be alright. 
​Please offer any advice you might have. Anything can help.