Welcome to SR! There is so much support here, so please post, share, read, and learn. I so relate to what you said about "beating a dead horse for 12 years". My alcoholic sister has been drinking for 15 years, and I probably begged, pleaded, and reasoned for her to stop. But she didn't, because she isn't ready to. As you've probably already figuring out, they won't stop for you; they will stop if/when they want to. In the meantime, you can make things better for YOU regardless of whether the alcoholic changes.
Hope you'll stick around, and sending you hugs!