First off I'd like to thank FirstLight for this thread. Then I'd like to thank every single person who responded.
Being a codependent parent is the most confusing thing in the world. Don't want to be too tough, and push them over the edge, yet can't keep trying to live their lives for them either.
Your daughter is an adult woman. You are clearly a loving mother who has done, and would do anything for her. Its time to pull back, get some reading materials on codependency, and create boundaries that you can live with and not waffle on when things get tough.
I met a great gal on this site a few years ago, who was an active addict for years and managed to get clean and is now helping others get clean. My 18 year old daughter went to rehab in December, and the day she came home, I asked my friend what I could do to make my daughter comfortable, keep her safe, etc. I was thinking she would say things like "Be gentle with her" or "encourage her daily" or something along those lines.
She said "Create boundaries and go to Al Anon" Not what I expected, but the more I read and learn, its the only way.
Good luck in finding that balance that works for you! xoxo