Yes, I have had experience breaking up with a friend. I won't go into the details because four years later it is still extremely painful to think about.
Perhaps her drug use has caused her to behave in this jealous and territorial way. I'm not trying to make excuses for her, but it seems that her drug use could be a major cause of her problems.
Subtlety doesn't work with her so you must be direct just as you would with a boyfriend. I saw something about this very issue on an episode of Oprah. They discussed ending toxic friendships. Here are the links:
http://www.oprah.com/living/lifemake..._tracey4.jhtml
http://www.oprah.com/living/lifemake...cheryl_g.jhtml
I hope that this helps. I think that if you treat her with compassion and respect, whatever you do will be an improvement over what is happening now. This is a really difficult and painful situation. I wish you the best.
