As far as "tipping her over the edge", that would be HER choice. She's already lost a lot and continues to drink. I'm sure you already "get" this, but just wanted to emphasize that she is responsible for her own actions. When I was using (I'm a recovering addict), I would use ANY excuse to use - good day, bad day, sun was shining, someone hurt my feelings. It was never anything but an excuse. I could have just as easily used those things to choose recovery (and eventually did).
Hugs and prayers,
Amy