Hot take: the worst type of people are those who will hold a grudge and never forgive.
This sentiment goes to EVB, but people obviously make mistakes, and they grow and try to move on. Especially when you had a previous friendship and knew each other, it is a reminder that people make mistakes.
And when someone tries to move on, they should not be known for it, nor be exposed for something from a while ago, and you STILL mention it. You're being immature.