I had a co-worker who managed to push my buttons in just the right combination such that one day I lost it and let him know exactly how much I didn't appreciate him. It was a tunnel vision moment and I am glad I didn't let it go further, but I went outside and cried like a baby for letting myself get to that point before apologizing to him. He continued to behave how he did and it got to me once more, but I did my best to limit my interactions with him and to go through my manager when possible. Since my manager was in the room during the fateful outburst, he was quite happy to intermediate. It had no negative career impact, but I was shaken by it and I think in any other situation, I would have been reprimanded formally or something.

I can't say there is a lesson in there except, don't let yourself get to the point where you are unable to maintain your professionalism.