What are your first principles (rules you've developed) in your life?
People who make me feel like crap or worse off then when I encountered them consistently are written off and out of my life
Doesn't matter if its family, nobody is entitled to your attention and suffering and it does nobody any real good for you to succumb to the inevitable dysfunction it creates in your life and relationships and also material conditions.
Probably my favorite realization in life was that I might be wrong. Always, no matter how confident, we are all wrong sometimes. Even about the most basic facts, we could be wrong because brains are weird. So, I just try and minimize that while recognizing it.
And learn how to defend when you're not. Some assholes use it as an excuse to divert blame to the guy who tends to admit fault, even if it's not actually their fault.