teenager girl problems

i have been dicvorced from my wife for over 15 years and i have a 15 yr old daughter. i paid child support until she was 11 yrs old and then she came to live w/ me and the child support was ended by the court. since living with me we have had some problems but her mother has begged for her to come back and live with her several times and we have tried letting her go back and every time it ends up with my daughter having trouble in school and behavior problems, this last time about 4 months ago her mother got my daughter in such an uproar that i let her go becasue we just couldn't handle her and her mother( i have a 5 yr old with my wife of 12 yrs) my daughter does not want to go to school, does not want to stay in class and has lots of attutide problems.
here is my question, we have joint custody, at what point am i no longer legally respondsible for her actions, as far as going to school and such. i dont want to just cut her out of my life but her and her mother are wrecking my 5 yr. olds life with all this drama and i dont want to have to pay a fine or worse go to jail over her not going to school or getting into trouble.
please help, im at the end of my rope

[Law200]

You are partially responsible until she is 18 normally so you may just have to get back to work on resolving this -- one way or another.

[PapaJohn]

Originally Posted by worried father

at what point am i no longer legally respondsible for her actions,

Pardon me for being a bit harsh here but I find that comment to be very selfish. All you're worried about is being legally responsible?? Don't you care about your daughter's well being? Have you even thought about counselling for her and you and her mohter? Not marriage counselling, parent counselling.
When teens act out like this there is more than likely a psychological reason and therapy and/or counselling often helps.