I totally agree. She cannot continue living like this. Her mental health is severely at risk and the physical wellbeing of her and her other 2 cats. This has been going on for long enough and I truly believe that this cat is not fixable.Have you checked the different organizations in your area to see what kind of options are out there? It doesn't sound like this is working well for either you or your cats.
I have fostered MANY cats and kittens in my life, from domesticated to feral and I have NEVER seen nor heard of a cat this bad. The closest I have ever encountered to this was when I adopted a 3 year old Persian. She was EXTREMELY anti-social with other cats, and even kittens! I took her to the vet, where she was put on an anti-depressant, and you wouldn't even know that she was the same cat. Afterwards, she would even allow still nursing kittens to try to nurse from her (I kid you not)! I will look in my paperwork to try to find out what medication it was but for some reason I think it may have already been suggested in this thread.
In any event, I truly believe its time for Catluvs to contact an organization that will take Cc off her hands.
She has done everything she humanly possibly can to help/fix this very angry cat, and I truly believe that Cc is not fixable.