I had an obnoxious person troll me, so I downvoted everything they've ever posted.
Why did you decide to downvote everything as a reaction to them?
I hope that I made them feel worse by this.  This seemed like it was the only thing that I could do.
I understand how you feel. I would be tempted to do the same thing. But it might be good to ask, what are you really accomplishing, ultimately?
Ugh, I can't believe you would try to make me feel bad.
I'm not trying to make you feel bad, I'm sorry. I'm just trying to understand exactly what goal this accomplishes. Perhaps it is better to devote your energy into something else productive?