She has broken numerous items in my home and often enters my bedroom (I was forced to put a lock on my door due to her stealing from me) when I am trying to work or sleep and refuses to leave, effectively holding me hostage until I give into her demands. She stays up all night on the internet (I can't just turn it off because she attends online school due to her antisocial tendencies). She refuses to listen to me, won't clean up after herself, leaving her room, the bathroom and kitchen filthy, and constantly warns and threatens me about what will happen if I don't do what she wants. She has not physically abused me yet, but I fear it is only a matter of time, especially because she is a very large girl and uses her size to threaten me. Do I have to put up with this until she's 18?
As my colleagues have answered, you can call the police and probably should. You can password protect your computer so she can only use it when you log her in, which keeps her off it in the middle of the night. If she has a cell phone, take it away. Don't buy her anything but food, and only healthy food. When she threatens you, be ready to "threaten" back with what your next steps will be if she cannot behave. You should also be seeking assistance from CPS/social services and finding other juvenile resources. There are programs available to try and work with her, including shipping her off to "boot camp" or boarding school if she cannot behave at home. Your child has become a bully, and needs to be dealt with in the same manner that you would deal with any other bully.
You can call the police whenever she does something illegal. As long as it is not a crime of serious violence, she would likely be charged as a juvenile. If she crosses the line and strikes you, it would be considered Battery Constituting Domestic Violence. You can also kick her out of your home if she continues the behavior.