I have seen and experienced a fair share of workplace bullies and they all had an overwhelming lack of introspection in knowing, understanding or even caring how their behavior affected others. It was always all about them. I joked about one who I wrote about in work gripes. For "normal" people, if you have an issue with one or two people, it could be a bad day or just personality, but for a bully, if they have a problem with 20, 30 or more people, it's all of them who is at fault. Never do they ever think, hey, maybe I need to change how I behave.

Only external force or the threat of force will get them to behave and only while that hangs over them. They thrive under weak leadership where they will not be held accountable for their unacceptable behavior.

That was a wonderful letter that you wrote and I think you hit that person's issues right on the head. Having a good support network like the one here is so critical to surviving that toxicity.