(((13))) - Welcome to SR, though I'm sorry for what has brought you here.
You're not weak. If you read around the other threads in this forum, you'll find you're not alone. There are also some really good threads called "stickies" at the top of the forum..they're permanent but a really good place to start.
Though I never had kids, I've been where you are with loving someone who is an addict. This site has been a huge help to me in realizing *I* deserve more than an A (addict) has to offer. You do, too, and so does your daughter.
BTW, I'm also a recovering addict, I turned to drugs to deal with my A's behavior? I have loved ones who are A's and I'm finally realizing I don't have to accept their using.
A lot of A's are great people...except when they're not. Even people without addiction issues can be like that.
A book you may want to read is "codependent no more" - it's really good and I never even realized I WAS codependent (codie) until I read it over and over, then years later discovered this site.
Hugs and prayers,
Amy