We must take responsibility for our own actions and accept that we are not responsible for the behaviour of others.
Ex’s walk their own path, just as you walk yours. You must not lay blame for their actions on your shoulders if you left them and actually, even if you didn’t!
Cut yourself some slack and understand this can be incredibly hard to do, particularly when they are behaving in a vile or out of character manner.
We all have the power to curb negative responses to the actions of others and for sake of our own inner peace if nothing else, we should endeavour to do so.