Take a deep breath
Critical feedback is hard to accept for anyone, not just you. It hurts to know that you are not perfect, the world is not love in with the way you are. And unlike many cliches, they are probably right and it is up to you to make changes in your life for the better. For all its obviousness, it is still not an easy thing to do. So if you are sitting in front of the one who has given the feedback, thank them and tell them you will seriously consider the feedback given to you.
Try not to feel enraged and get defensive. Don’t get apologetic without understanding thoroughly. Don’t try to pass on the blame or call it a misunderstanding by the other person. Just breathe and let the feedback sink in your head.