Is it normal that sadistic thoughts turn me on?

I have a problem.. I can't control it but when I'm angry or irritated I have extremely morbid and disturbing thoughts and I get turned on. When I say morbid I mean the thought of someone being tortured, sliced open, really graphic things.. I would never hurt someone or act of these thoughts but it does turn me on and sometimes when I have sex with my boyfriend I think about him being hurt.. I don't really know why but.. Yeah..