hi losingfaith...I don't know if this is your first post here on SR, but if it is...WELCOME! I'm very glad you found this place; the support you'll find here is awesome.
Sounds like you're already on the path of detachment. Have you considered joining Al-Anon to get the support you need?
Guilt is totally normal but please remember the 3 C's of addiction:
You didn't CAUSE it.
You can't CURE it.
You can't CONTROL it.
So when your sister throws insults or blame your way, remember these. Her addiction is entirely her choice and no one else. You do not have the power to change her or help her, so it's best to step back and protect yourself. If and when she does find recovery, it'll be her own journey and not yours.
I agree with Wife about calling CPS anonymously.
keep posting!