There are a few things I can say. I honestly think that you shouldn't listen to the voices in your head and you need to find something else to distract yourself. Probably the reasons why this is happening to you is because when you were little you had those nightmares and all, and I'm guessing you might have started to believe in them, that there were odd things in this world that were meant to be hidden. What I'm saying is that since you were younger, you could believe anything, and these nightmares of yours kinda left a scar on your mind, and they keep troubling you and interrupting your life. That's probably why you started hearing those voices. They're obviously not real so listening to them would only increase the problem. Right now you're trapped in this massive ball of suck, and you can't get out because you're believing that you're going insane.
You're not going insane, it's all in your head. Ever since you were little, because of those dreams that might have given you a small thought that something was going on with you, and it has followed you up till now. You need to free yourself from this thought, and you need to believe that your mind is pure, because I believe it is.
Killing yourself won't make you accomplish anything, it only means that you will lose everything.
