Originally Posted by
Katchie 
If he has been drinking tell the kids to NOT get into the car with him and to call you IMMEDIATELY to pick them up.
Good advice. The fact is - it doesn't matter who the driver is... tell your kids that they are NEVER to ride with someone who has been drinking and that they are to call you for a ride, day or night, regardless of the circumstances.
Tell them this applies to Everyone and at all times, it has nothing to do with your ex, and everything to do with their safety. Make sure they have the ability to call you whenever they are in a situation where this may occur.