"The best thing you can do for Emily is to encourage her to talk to a trusted adult, whether school teacher, counselor, pastor or any other adult who is in a position to give her good guidance."
Yes, yes, yes. The level of control you want to exert in this situation and the hubris you exhibit in your desire to appear mature is truly frightening to me. This is, in my ears, the start of a terribly controlling possibly abusive romantic relationship with a very young girl who is being controlled by her family, and now has fallen into a relationship where she is in danger of being totally controlled by you.
Your insistence that she tell you exactly what the discipline situation is, what her parents have said, your expectation that you have contact with her every single time you want it and demand it, that you did not listen when she explained that you were not to come over, YES, you ARE the problem in her life right now!
As far as you know, no one would be hitting her, disciplining her, taking her phone, threatening anyone except for YOUR actions. You need to go away for a few months and totally drop out of this relationship you have so massively built up inside your own head instead of having your little "I'm so mature, now we have to figure out how WE'RE going to handle this situation...you're going to run away to my house when you're eighteen, blah blah blah......" plans laid.
If I were her parents I'd be taking every legal action necessary to make sure you stayed as far from my daughter as I could keep you.