Here's what you do.
Buy a bunch of instant food, bottled water or sodas, that kind of thing. You following me here? Now take all that junk up to your room. Just toss it anywhere. Close your door and push something big and heavy against it. I like my bookshelf, but beds, dressers, desks, anything really will work. If you have a window that's not boarded up, I recommend cracking it open a few inches.
Now don't leave your room unless you have to shit or get more food. Don't respond to her at all, even if she shuts off your power for weeks. Hit the library sometime and get books if you can't use the computer. The point is that you're sending the message taht you won't submit to her, and by not telling her what she did wrong, she can't attack you for pointing out her flaws. This way, she'll be forced to realize her own faults and how valuable you are.
Don't be rude about it though. Don't blast your music or write a note saying "fuck you" and leave it somewhere. Just fade away. If she works, you should know when it'll be safe to use the bathroom/get food/shower/do laundry/whatever. But just vanish for a few weeks until she tells you that she'll make real change and stop abusing you.
Don't cave in and be strong. The hikki life can be very stressful. Only the hardest of the hard can maintain it.