Are they human?

I have been thinking a lot about this, as I try to come to terms with my rage at him.
If we dehumanise them, consider ourselves "victims", it is so easy to rage at them perpetually (as I have done) and say mean nasty things. It's a way to vent hurt and hatred, as well as a way of trying to even the score, get revenge, make them suffer (even if we think they have no feelings and are inhuman).

But what if they are human, and do suffer - does this make our rage unjustified? Am I in the wrong for messaging him a message of my extreme hatred and ill will towards him?

basically, should we consider them decent human beings underneath, even if we could not access that, and treat them with the same respect everyone else deserves?

And if we have treated them appallingly, worse than they may have treated us, should we apologise to them?

I am facing up to the fact that I am far from blameless in this interaction, and that in many ways, I am at fault.