Sweetie, She is right where she needs to be. She may be a tiny little thing, but she has managed to survive the horrors of drugs and being on the streets. She has lots of strength...the next couple of days may be painful as she withdraws, but it is it is not life threatening and the pain may help her to want to stay clearn.
You're so strong and loving...You can get through this. Close your eyes and visualize her higher power wrapping her in protective arms. Let him do his job, dear one. Hugs and prayers and please get some rest!