(((((NSW)))))) Hugs to you and lots of prayers for you, your daughter and grandson. I know this is very difficult, but it truly is the most loving thing you can do. Opiate withdrawal, from what I have read, is very painful but not life threatening, unlike some other drugs. She will be okay and getting past the point of being dope sick may help her to find the strength she needs to seek recovery.
I hope you can rest easy tonight knowing your little girl is off the streets. Hugs.