Awww, Kimm, it hurts to watch our loved ones stay on the path of destruction, and as much as it hurts, you have done all the right things. Calling the police when she indicated she might harm herself, refusing to fall for her "just for 2 weeks" ruse, and most of all taking care of yourself no matter how poorly she is taking care of herself.
As I often say, WE are not their only option. WE are not even a good option because to live with active addiction doesn't help them, it just pulls us down with them.
She knows where help is, detox and rehabs can help her where you or your brother cannot. The Salvation Army program is free and very good. When she is ready, she will take a better path. In the meantime, protecting yourself from her calls and attempts to drag you in, is a good idea.
Hugs