What words or saying really effected you/changed your mentality/ helped you etc
Maya Angelou's words "when some one shows you who they are believe them" helped my leave an abusive situation. I realized the abuser was exactly that and they won't change so there was no point in trying to 'understand'/'excuse' their behaviour.
I keep this in mind now when in all my relationships. It's actually helping me to undo some cognitive dissonance over some siblings that are the lovely golden child and being told from.childhood that they're sweet, lovely etc but now I realise actually just how awful they were/are to me.
Along similar vein is "how they treat you is how they feel about you". This really helped me open my eyes to one particular sibling and their nastiness towards me.
Another saying I am trying to implement in my life retrospectively in some cases, is "be careful of what you tolerate; by what you tolerate you teach others how they can treat you".
Trying to step back from my 'pick me' 'begging for some kindness' behaviour, making clear to people that I am not happy with their behaviour.