Michelle,
You are not alone--in either your frustration or your pain. My son is a 39 year-old alcoholic. He was living at home until he decided to leave last Monday. We have no clue as to where he is or how he is--though we're certain he is drinking.
We've gone through this in the past--several times. We've always answered his calls for help and taken him back into our home when he asked. This time, we are determined not to enable him again. We will try to respond with love, but not provide a place for him to pause until his next binge.
We all love our children (and spouses and siblings) and feel that somehow we should be able to help them "conquer" their alcoholism. The problem is only they can decide when and if they will quit using. Our well-intentioned "help" often really does enable their behaviors. (That's a hard pill to swallow--but seems to be the cornerstone for building a survival technique for parents and significant others.)
God help all of us.