I he's drinking then he's probably using and it's not all it's cut up to be at all.
She has him now, she also has all the problems and baggage that goes with him...and when she's had enough of him he will move on to his next victim. That's how it works with addiction. I watched my son go from one relationship to another in days. It was part of his sickness that he could neither make a relationship work nor could he stand being alone with himself.
You may not see it through the pain right now, but you are better off without him. Active addiction means a healthy relationship is simply not possible.
Stay focused on you, keep going to meetings and working on healing and one day soon new beginnings will bring you happiness and better tomorrows...I promise.
Hugs