Why am I reading this only now!?
If you haven't read this MetaFilter comment from 2011, please do it. It's about why some people stay in shitty/abusive relationships, and why some people are judgemental about others. It can be a real eye-opener for many, and it cleaned up my mind about several topics.
(CW for learned helplessness, feelings of worthlessness, abusive family relationships, and cruel behaviour in the animal kingdom.)