I also live with a werewolf........but he is more a protector, an alter ego.
Knowing the difference between being one and having one as a imaginary friend that makes you do bad things are two different things.........I often think I'd love to be one but well thats just not possible....... I have done horrendous things in the past in the name of my werewolf........but there are consequences.
Your friend needs help to understand the pathology behind "wanting" to be one......and actually thinking she is one. It sounds like her behaviour is picking up momentum.......you are a good friend for wanting to help her but the path will be tough.......she will not let go easily.......you need help in your intervention.
If you wish to discuss how I "tamed" my friend, feel free to PM me......
Have faith.......she will be alright