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.
I'll focus on people. I avoid people who consistent or egregiously:
are assumptive, gullible, or fallacious.
expect me to be assumptive, gullible, or fallacious.
are eager to violate the others' autonomy; for example, the "I never take a «no» for an answer" ones.
defend their actions based on intentions (instead of responsibility, outcome, or info at hand).
expect me to apologise for things they know I have no blame for.
claim that fighting back makes me as bad as my enemies, i.e. who expect me to become a punching bag.
Note: "consistent or egregiously" is key here. A brainfart or a derp is fine; but some things happen too often, or are too strong, to be considered simply brainfarts.