I once had this bit of conversation with a man who soon became my mentor for a while:

him: "I see it."
me: "You see what?"
him: That thin blue line running across the center of your eyes."
me: "What in the world are you talking about?"
him: "You could take someone's life in a heartbeat and think nothing of it."

I have never been in a fistfight in my entire life, but I have occasionally bluffed my way past them by telling people we could "dance" if they wish but that one or the other of us would be dead at the end and I did not care which of us that might be.

I can easily make a list of reasons as to "why" I have a lifetime of deep-rooted anger even I cannot actually justify, and there have been times when I have had to really concentrate on keeping my hands down at my sides while walking past someone with a hammer or some other heavy object in my hand lest I bash a skull just to see what actually happens and/or how far the blood might fly...and I once had to have myself locked up (a voluntary commitment at a psych ward) in order to be certain I did not commit a triple-homicide I felt coming on and absolutely did *not* want to commit.

It will possibly be tough to find a trustworthy therapist who can handle hearing all of that kind of stuff without missing the fact that we are sharing it while in search of (or in order to try to find) help, but please do try to find one. Prison life was rough enough for me way back in the late-70s, and I am quite certain it would be absolutely miserable or even deadly for you today.