I think SA Girl's point was that actually posting about a specific incident you had with someone, and then there are pages and pages of support for you and insults towards her (albeit nobody "knows" her) is a bit.... Wrong.
It's very common on here, and I have often posted saying I think it's off, and now usually don't bother as it's just part of BH.
Imagine that woman was a member here and saw that? Imagine you knew there were pages on a forum about your friend/daughter/mother/whoever? Not nice.
And agree that you don't know what that person has experienced that day. Sometimes instead of getting angry and worked up about something, try smiling at them, asking if they're ok. If they are genuinely just nasty it will disarm and confuse them. And if they're having a bad day I am sure they will appreciate it and karma will repay you. Win win.
My friend was absent minded and bumped into someone once. The feral woman hurled abuse at her. My friends mum had died the day before.