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For a while now I've been struggling with something, I feel like I have been split in half, one side is average me, the other is an inner darkness I can't control, I lash out and get violent sometimes but I don't even know I'm doing it, Ive harmed myself and not been able to stop it. Idk what it is but it's like flicking a switch and I'm someone else. Dark and angry and wanting to hurt people around me and I don't trust myself to control it. 

Does anyone else get this? I was wondering if it's BPD or a split personality or something. I have no clue.