I'm with CD on the phone issue, that might be worth looking into if the authorities start squawking about charges. You never know with these messed-up courts, they might pull anything under the guise of "protecting the children"---while the granddaughter causing most of the problems is clearly gaming the system. Saddest part is that it's no picnic being a ward of the state... the kids will learn to rue their folly, but by then it'll be too late.
Right now you're upset, and justifiably so, but don't bring that anger into the court hearing... and if they start squawking about "abuse" and how you're such a monster, you might explain to the judge (or whoever is in charge) how you took care of the kids for many years at your own expense, aye? Relinquishing guardianship of the ungrateful kids to the state would not be the best move for the kids, but it might be the best move for you if it means avoiding bogus charges...
It sucks to find yourself in this situation, but you also want to protect yourself from any bogus charges or 'black marks' on your record... I understand the part about wanting to cut the kids loose to let them learn the hard way, as I'm not the most patient man on earth, but try to keep your mind open to reconciliation, especially if the kids start changing their tune. Maybe they'll see enough in temporary "protective custody" to make them reconsider your points of view.
If things don't go your way in court and you start to feel overwhelmed, ask the judge for more time to seek legal counsel or prepare a defense. This from a hand who was falsely charged in Kalifornia and shot down multiple fake charges in their own rigged courtrooms, all while defending myself, go figure. Never wanted ANYTHING to do with ANY of it, but I was dragged into the public-fund-wastin' fiasco and I was forced to protect myself and my good name.
Had six months of my life ripped off the third time around, fighting the phony charges from the inside after my bail was jacked to half a million dollars (no record). All charges stemmed from my efforts to expose corruption in the D.A.'s office and the C.P.D., and I shot down the phony charges round after round. Hopefully you won't have to face the same ordeal, but don't expect honesty from ANYBODY in court, including cops, state workers, attorneys, or even the judge.
Having said all this, try not to dwell on things until the hearing... I know that's a tall order, believe me, I know, but it won't do any good dwelling on it. You've already been dragged into this situation and now it's a court matter, and such matters can drag on for weeks or months... but things might change at the hearing. One tip I can offer: write out a simple statement to read to the court, so you don't forget any important points when it's your time to speak. Good luck!!!