It sounds like you've got a lot of insight in to yourself too - talking to you now, I find it hard to believe you would bully anyone. But I've seen how family dynamics can drive that kind of behaviour, especially since you know that something is wrong with the situation but you don't necessarily have the perspective at that tender age to see where the abuse is actually coming.

I can imagine that doing an incredible number on your head, and props to you for rising out of that anger and anxiety and lending a hand to those who need it. I hope your younger sibling can with time understand that the injustice of your caregivers were the main driving force.

Hard to forgive what you can't forget though. My brother hasn't spoken to us in several years, but it actually makes me feel a bit warm to hear your perspective and knowing that he might actually be okay - thriving even - without us.

This all reminds me of one of my favourite comic strips: https://pbfcomics.com/comics/trauma-trooper/