When someone says something negative about you and you become defensive- many times that’s because deep down you know it’s true. You become defensive because it resonates with you at a deeper level and you don’t want to face it so you push away that realization.
You defend yourself.
You try to justify your actions.
You try to explain your failures as reasonable.
Criticism only hurts when someone points out a flaw that you know is true but don’t want to fix. If you’re real with yourself you will recognize that flaw and do what’s necessary to fix it.
If you truly know who you are, then when someone makes a criticism you can evaluate it without becoming defensive. You can realize whether that criticism is valid or if it has no merit. If it’s valid, adjust, and learn from it. If it’s not valid then you can easily brush it off.
Once you know who you are criticism becomes a good thing.