To correct something I said, I was thinking it's better if someone else than you to send her the books, because your relationship is so bad at this point she won't trust it to be a good thing and not care to read.
You're doing it wrong. I am surprised that what you are doing is even legal, not to mention you are giving homeschooling a very bad name.
We only imprison a suicidal person to make death impossible for her, having in mind that the person's life is her own and that if the person could think rationally she would want to live. This is never to be done at home, though. It's done in a hospital or clinic, because it's a place that will be hated and where the person rightly won't want to return to.
I remember being in a mental hospital ward as a young adult and thoughts going from "I hate the world and I wish I was dead" to "If only I could go out in the sun and get some ice cream." This hospital had a beautiful garden outside which you could see from the barred windows and a quiosk where they sold ice cream. Man, did I enjoy that ice cream once I was allowed to go out for it! When was I finally released from the hospital (on the condition of doing therapy, which I quit soon I could, because it was humilliating) my family took me out to the cinema, to buy videogames and I had no restrictions on Internet and going out with my friends (I was not a minor anymore, so I guess it was easier for them to respect me.)
The experience was undignifying and I still have a grudge against my parents for it, since they got the necessary documents to forcefully sign me into hospital. I still love them and we talk but I prefer to live in another country. I also never completely got rid of my suicidal thoughts up to this day (over a decade after) nor did the experience scared me out to try suicide a second time. Still, it might have solved the immediate emergency then. I don't know.
The most terrible thing about hospitalization is the forced medication, which is brain damaging and useless. The mind is not ill, just wrong.
So I'm sure there is a better way to help. But whatever you do, have this in mind:
One's home should always be one's home. It should be a person's private space. It should be a welcoming place where the person longs to be in. Your daugher should have her own room, her own computer, her own things, her own friends and her freedom back. She should not be spyed upon by her own family. That will just make her paranoid. If her own family is out to get her, who isn't?
Understand that a person is motivated to live when they can be free, when they can have a good life by their own standards. So help her get a life she wants to live. listen to her. What does she like? Get her more of that.
Also, get her some Ayn Rand. Ayn Rand is great because she gets to the roots of the self-esteem problem. Teenagers that read Ayn Rand love life, and behave like they are invincible. I wish I had read her then. Your daughter is more likely to not be influenced by bad friends when she learns why she shouldn't care for what others think. The Virtue of Selfishness is brilliant. Get that one or Anthem for a starter.