Hi Ravensong,
My heart absolutely goes out to you.
You have every right to use whatever "protective mechanisms" you need to use, to protect both yourself and your daughter. In my experience, the biggest mistake when dealing with addicted people is expecting them to behave rationally and make rational decisions. Oh, they may be good at fooling everybody else, but BELIEVE me, addicts are functioning on an altered state -- chemically altered -- and it is not even POSSIBLE for them to make rational choices.
Trying to have a rational discussion with them is even worse. Don't expect reason.
At some point -- and I was the addicted one -- the addict has to reach a place where is is less attractive or desirable to use than it is to get clean. As long as they are enabled and it is easy to use, there is no rational reason for them to choose to go through withdrawal. As we used to say in the 60's, "If it feels good, do it."
Well not any more.
You will reach a place -- hopefully soon -- where it is less attractive to you to enable her than it is to get tough with her. An addiction counselor once told me, "The addict is walking down a hallway with lots of doors, and ONLY after the only door that is not locked is the one to getting clean and sober, then they will choose that door."
Right now, you have too many open doors for her. She will take the path of least resistance.
Good luck, and take care of yourself first. You are no good to anyone if you don't.
FT