Is it normal that i get the urge to torture and kill people?

I always have the urge to hurt people. I will have fantasies of taking an innocent family and torturing the children to death in front of their parents. Sometimes it's just fantasies about beating up someone at school (but like getting them on the ground and then kicking in their face beyond recognition). It gives me such a rush to think about and I feel like I want to act on it, but I get frustrated because I feel like I can't. If I hurt somebody I will get into trouble and I am already on house arrest for doing drugs. I am always feeling emotionally dead. My therapist says that I have this level of apathy towards everything in life and that it is unlike anything he has ever seen before. I am not depressed, not happy, and I don't want to be either of those. I don't ever get excited, I don't ever really get disappointed, all I ever feel is bored. That's why I started getting into harder drugs. I find every little aspect of life mundane and dull. I don't have hobbies, I don't enjoy doing things, I don't desire things, the ONLY 2 things I ever crave are opiates (heroin and painkillers) and hurting people. I have had these sadistic desires ever since I was little, although they have gotten worse as I have gotten older. I am also a very emotionally cold person and I don't care about people's pain at all. I don't care that I have disappointed my parents and lost their trust because of drugs, I don't feel my friends pain whenever they are going through something hard in life. I know that sounds psychopathic, but I'm not so sure. I don't know if I have always been this emotionally cold, but one thing I have realized is that the better I feel emotionally the more I want to hurt people for fun, and the worse I feel the more I want pain pills. Is this normal?