Heya DII--
Bummer.
When you say approaching her what do you mean? You want to make a statement like, "I know you've been drinking." You can do that naturally, just remember, no expectations! If you're hoping to get a certain "response" from her, as you already know and FD said, don't waste your time.
Or is there some boundary you had set in place that now you need to enforce?
Is she working a program? Does she have a sponsor? Or a counselor/therapist?
Are you? Do you?
Hope you find some peace of mind tonight!
Peace,
B.