IMO you don't have the right to tell her to stop drinking. She is an adult and as such has the right to run her own life. If her drinking bothers you then leave, that's fine, just don't use it as a club to try and get her to change.
If she is not ready to quit and it doesn't sound like she is then it won't make any difference what you do. She will quit when she is ready and not one second sooner.
Your friend,