I've been in two situations like this where I eventually "WON". You don't simply heal. You don't accept that that just wasn't the place for you and move on. What you do is have your perspective on other humans permanently and irrevocably changed. If you are a certain kind of person who values truth and personal responsibility, you come to understand that the world is fundamentally incompatible with you, and are faced with the choice of living a meaningful life where you are constantly preyed upon and abused, or living a meaningless existence in which you betray everything you ever valued about yourself.
"If you are a certain kind of person who values truth and personal responsibility, you come to understand that the world is fundamentally incompatible with you"
This logic is flawed in that you are assuming no one else shares the same values as you do.
That's not an assumption embedded in what I said. The fact that I identify with Brain's circumstances shows that I'm aware and believe in the existence of such people other than myself. The reason that I "won" my battles is a result of at least some shared values and perceptions of others around me. It's not about that, it's about the reality of what awaits you if you want to live your life a certain way and can't accept living it differently. That is all.
You have to resolve the fact that his values existed in that sphere. If his values exist then surely there are others. The whole him against the world defeatism is ultimately flawed logic.