She may have a drink problem, but as someone else said, she may just be using it to kerb anxiety or stress. It doesn't necessarily mean you should stop being friends, but may re assess what you do?
My best friend from uni drinks a lot more than me. She is married but they don't have DC, a choice as she preferred developing her corporate career. She and her DH drink at least a bottle each a few nights a week at home, to relax. I think her need probably started early on in her career, going on work nights out. I know she has mentioned drink driving a long time ago, though she now works in London so that wouldn't happen now.
I think as the years have gone on, they have got used to drinking lots and they have had to up the quantity to get the same level of relaxation.
I was never a particularly big drinker, but have tailed off to virtually nothing through having kids, needing to be sober in case of emergencies when DH working away, and being susceptible to migraines, more so after drinking.
For years she has made comments about how I need to drink more, I just ignore or laugh them off. She cant understand how I can exist without the level of alcohol she drinks, I cannot understand why they need to drink so much. They came to visit us last year (I have generally met her and other girls for girlie weekends) and had got through a bottle even before dinner on first night. DH and I had a glass each, maybe a bit more, all evening!!!
I would never drop our friendship, we are now in mid fifties, so been friends a long time, I have just accepted we have different attitudes to/need for alcohol
Given that this has happened before, suggests she needs alcohol for whatever reason. As a pp said, maybe try and arrange meet ups in the day? Or if she drives, that she has to drive to (assuming she wouldn't drink then drive?)