Liberate yourself and truly forgive.
To be unfuckwithable is to be truly at peace and in touch with yourself. Nothing anyone says or does bothers you, and no negativity can touch you.
When you learn to truly forgive, you become unfuckwithable. Someone could be mean to you, and, yes, you’ll take defensive action and protect yourself if necessary. But you’re able to go on with your life without having to waste your energy on them.