I have had the thought cross my mind about killing someone who really pissed me off. I had an ex-coworker of mine ask me the same question, did you ever think of killing our ex-boss? I answered yes. Then he asked, would you ever do it to which I answered no.
He said that's the difference between a sane person and an insane person. We all have those thoughts of shooting up a person who has pissed us off but only insane people actually go through with it.