I'm not used to having the parents against me.
And I'm only a veteran of two withdrawals, Rroma and Gunner; both of those eventually ended.
(I guess, however, and now I can say "oh, but of course",! that this is significantly because I groom exogamically, so I build my relationships with parents from scratch and there is the theoretical possibility of 100% leaving their lives. Whether I groom friendly or hostile, I can always withdraw. Family? Not so much, even not at all. I suppose now I found a silver lining to the low degree of trust I have in my family).
I would think, with the mail that you were written, (and again, I'm taking from my own experiences, re: Rroma and re: Gunner) that you should stay away. I know it's impossible, mentally. I know it's draining. I know it. But there really is no alternative for her safety and stability. If it was only about you, then I'd say if you're brave or insane enough (a fine line) then go for it. But it isn't just about you. She will be on the line. And she will suffer the negatives more than you.
Count the days until she is 18. Pray (yes, that word again) that it's over before then. And wait for her. As I did with Rroma and Gunner.
Again, it's not a perfect analog, because parents were with me with both and it was external peeps who weren't. (Who nonetheless had the power to stop us from seeing each other). With Rroma, those people disappeared from her life by themselves with no action from me (or her and her family). With Gunner, she came around to understand me and understand the sitch on her own and she herself found the ways to take me back into her life. But again, with parents on my side.
I know it's impossible. But stay away. You're dead until there's a doctor by the bedside telling you that after all you woke back from death.
Certainly don't give her the phone. Keep it under lock and key, waiting for her. As I kept my heart for Rroma, and all the more so for Gunner. Because at this point even a wave is suspect; an expensive gift is a total No. I know you don't intend it so, but it looks like you're buying her, and it looks like you're engaging in a bidding war with her parents for her loyalty where you'll be willing to outspend them so she prefers you out of greed.
I'm sorry I have to tell you this. I know that's the thing you least want to do.
But, as you said yourself: this is about Her, not about you.
This is how you will be best for Her, even if not for you.
Remember I'm just a few hours more in the same direction: just reach the opposite end of the desert and you'll find me.
Cuteness is to die for
Cuteness cannot fail
Cuteness knows no limit
Cuteness will prevail