I didn't intend to. I didn't recognize that it was what I was doing. In fact, I thought I was defending myself against an unfair attack. And while that can be debated, what I failed to recognize was that the pain I felt from this attack paled in comparison to the pain I had caused, however unintentionally. It also paled in comparison to what was added when I wrote a diary a few days later about the incident.
I've been thinking of this a lot the past few days, trying to find the lessons to take away from this experience. I don't want to pull back on my self-expression, but I also don't want to say things that cause others pain. As such, I will try much harder to avoid being reactive myself, and be more forgiving of those who I feel have wronged me. I will also be more attuned to the context of the threads in which I post and try to restrain my impulse to be a smart-ass when it is not appropriate.
And to the person I harmed, I am so, so very sorry for the pain I caused you. I also hold no ill will over any of the things that were said. Please take care.