Pass the burden to the police
It's not our job to watch over drunk drivers. WE PAY, IN OUR SOCIETY, A POLICE DEPT. TO DO EXACTLY THAT!
Ok, I'll stop yelling.
Police dept. Number 1 job is PUBLIC SAFETY.
Call. They can even start to respond to you by first name, heh...who cares...maybe the squeaky wheel does get the grease over time.
I'd give the same advice to anybody on here. You know a drunk driver? Call, rat them out. Mr. Cop--She's at it again. She took X route, she's driving X car make/model, she's going to her usual haunts--you know them, I've told you them before.
At some point, the police dept., unless it's run by the mafia, and she's part of the familia, will respond and seek to find her, and never tell her who called them.
It's their JOB! We PAY THEM to do this!
Put the pressure on them to do their job, then sit back and relax. You did your part. Now it's up to them.
If she kills somebody, or herself, your conscience is clear. You tried, and that's all any of us can do.