Constantly invalidates your feelings
Takes advantage of both your kindness and forgiveness.
Utilises your traumas to their advantage
Engages in victim-blaming behaviour and never hesitates to belittle you
Never bother to fix their mistakes, sees themselves as above consequences or just "doesn't care" about your feelings yet are the first ones crawling back to you to fix their problems.
Constantly lies to weasel their way out of facing their actions and when confronted with proof they will protest, telling you to leave it be or that it's not a big deal, this of course only applies to you, now, anything they feel is priority and god forbid you put yourself first after having been thoroughly psychologically abused.
They relapse back into patterns of faux apologies that are never followed up with a change or any attempt to undo the damage, very moral grandstanding and conceited, will never see or care how how their actions affect others.
I have had plenty of experience with toxic people in the past, particularly the last one I came to despise, and I'm a naturally nurturing and gentle person who gives anything up for their friends, for me to hate a friend they ought to be the worst, someone who has proved beyond reasonable doubt that they want to inflict pain
Surround yourself with your true friends, those who you know care about you and have proved themselves trustworthy.
Don't rant at the person who hurt you, this is extremely difficult, when one's trust has been violated in every way imaginable, to give the cold shoulder and pretend that person doesn't exist is excruciatingly hard, but it is for the best, if they know their actions get to you it will only make the cycle longer, break it.
Feeling invalidated is very common, especially when there's so much you want to get off your chest, remember that your feelings are valid no matter what.
Look at yourself in the mirror, are YOU happy with the choices you made? can you see a respectable moral individual who has done the right thing by sticking up for yourself? then, that's all that matters, nothing the toxic person says does.
Block said toxic person in each and every blog you have, usually they'll have plenty of blogs they stalk you with, even if blocked chances are they'll see your content, let them. They're no longer your business, nor is anything they say or do, as far as you're concerned they don't exist, it can be tempting to check their blog from time to time, when you feel the urge to do that, send your mutuals nice things instead! they'll appreciate it, and unlike the former option this is time that is very well invested.