Should I kill myself?

Well, to start off, I've been extremely depressed since I was extensively abused as a child. And I've bottled up all of that emotion since then, I'm 17 now. And my sister (she raised me, she was my mother figure) won't even acknowledge me anymore. She only talks to me if she want's something. She was my best friend and now I'm just stuck on my own. If I go to a psychiatrist they'll just send me to the psych ward (It's already happened once, didn't help me at all. Just made me even more depressed). The only thing I have left is the thought of me ending it all, it's the only thought that brings me a slight bit of happiness. The thought of ending my life makes me think that there's a way out that will leave everyone like normal and me happy. I just don't know what to do. Please help...