You're liable for the car itself. If she doesn't pay, or there's damage on car when returning the vehicle.
As for insurance portion, it has nothing to do with you. As long as you're not insuring it, and car isn't in your name there's no way for it to ever ding your insurance.
And I really hope she doesn't drive drunk. She might not be insured if she gets in an accident. THEN YOU'RE FUCKED. She could get sued by the victim, then when she's too broke to pay for the car then whoever co-signed is now liable for the whole replacement cost of the car.
Not trying to scare you or anything, but yeah, if you worried about her hitting someone when drunk she probably shouldn't be driving to begin with.