This particular instructor sounds as if she was too harsh ... but ... it is not anyone's job (even your mother) to always say positive things to you. Sometimes, people need a good "kick in the butt." If you screwed up and did not adequately prepare, then you may have needed to hear that. Not all feedback SHOULD be positive. Sometimes, we need negative feedback to help us see our mistakes and take personal responsibility for them.
I am sorry that this instructor was overly harsh. I'm sure it wasn't necessary as you probably felt bad enough to begin with. But that's behind you now. It's time now to learn from your past mistakes and move forward. Pick yourself up, dust yourself off, and start preparing for the next time you take the exam. If your school offers actual assistance with NCLEX preparation, take advantage of it. Don't let your personal pride get in the way of your use of their resources.
Good luck to you.