My heart goes out to you. My parents are about that age and I know I will have to face this soon as well. Your post will stay with me and I'll remember this when I'm in your situation. So thanks for sharing this.
Like SomeoneSomewhere said, your mother must be very proud of you right now. I hope your brother can address his drinking at some point. Life isn't easy, but at least if we're sober, we know what we're feeling and doing is genuine.