Thank you all for excellent advice and encouragement. It wasn't until now that I recognized how, little by little over the past months, how much of her adult responsibility I've taken ownership of. No wonder she's regressing.
I will give Al Anon another chance. I've been thinking I could figure this out on my own, but I can't. There are some things about Al Anon that make me uneasy, but I'll just have to get over that.
Again, thank you very much. You've given me a lot to think about.