I sympathize. I'm single-parenting an almost-teen girl with an alcoholic father who shows up just often enough to create chaos. I too find it very difficult, and I imagine it's only going to get tougher as she gets older. She's a great kid, but like you say, even great kids aren't always mature enough to make good decisions. I end up doing all the discussing and worrying in my own head because there's no one else. I don't think I have any great advice to offer except to say that you aren't alone.