Leaving her might actually be the best thing for her. It might snap her back to reality and have her realize that her self-harm doesn't just harm herself, it harms other people.
But, it could backfire with her taking a jab at her jugular because of it.
I don't want to leave her. She knows it harms other people. But, it is an addiction. And I don't think she meant for it to just be self-harm tonight.