@djjd62,
Beating your kids to show control is n act of desperation. It doesnt work and will result in you losing her confidence, trust, and love. You decide, but in my mind what you did was criminal, so dont expect any reinforcement.
What you may be missing is not that you have this CPS issue, youve probably missed the entire reason WHY her grades have slipped.
I had a similar problem with my little girl when she was 14. She went from an advanced placement student who was readying herself for early college admissions ,Then she just toppled from the perch and became the "kid from hell". It turned out that she was being Svengali'd by an older boy who was into drugs.
Stop worrying about yourself, pledge to stop beating her, get back on the track as a parent, and try to find out why she's giving up.
Ill bet that a boy with marijuana is behind it all.