Fortunately most of are not axe wheeling psycho-sociopaths with narcissistic tendencies, but lurking in the darkness maybe some anger, fear, lothing, jealousy and regret. Your're not plotting your coworder's demise, evan though he did something that made you mad.
My point is you recogonize the anger, but you need a way to deal with so it doesn't consume you.
You need to embrace it because it is part of you. but that's not all you are, and anger if you let it, passes.
We will work on this more in the weeks to come. Take a deep breath. this too shall pass.