"Great minds discuss ideas; Average minds discuss events; Small minds discuss people."
Best action is no reaction, enough becomes enough and you let it go because your an adult. You're not the person they thought you were, you're a better one!
Mistakes are a part of being human. Appreciate your mistakes for what they are: precious life lessons that can only be learned the hard way. Unless it's a fatal mistake, which, at least, others can learn from.