Nobody knows how close someone is to ending it. That's what you should think about when deciding whether to be nice or frankly and asshole. Some people might just be one step away from trying to commit suicide and a simple act of kindness, even just a hello, could stop them from doing. And of course the same could be said for the opposite interaction.
Being bullied in school sucks, I know personally. I got bullied while my father was serving overseas. I was told on a constant basis that he was going to get shot in the head or run over an IED. And it sucked.
I later got bullied again where I was harassed on a daily basis. I couldn't sneeze without this person saying something, running and telling the teachers and me getting in trouble because she was the mayor's granddaughter.
You did a good thing when you were in highschool! The world needs kinder people!
I don't like bullies at all like they think that they can do anything just because of few supporters like for real if everyone takes stand against them then they would fear to do that again ever in life, they just need to learn a lesson.