She probably feels exceedingly lonely inside. It's a very hard place to be.

People with narcissistic traits aren't subhuman.

I have narcissistic traits due to early childhood trauma and abuse. I still have a heart, I still care. But I also struggle with relationships - I try not to have any to protect others from myself. Doesn't make me feel much better.
People like your friend need the right kind of help to manage relationships, whether that be therapy or peer support or suchlike. It helps no one if they're discarded. True, it feels like you've been treated like rubbish by her. But maybe she feels rubbish inside, and it 's her unconscious way of protecting herself. It just comes out badly.