I had a similar experience with this type of meeting 20 years ago and it worked for me as I haven't driven with a drink in me since.
If this type of experience doesn't stop people from drinking and driving nothing will.
I will admit I have driven with people that were driving drunk when I was drunk which is equally stupid but at least I wouldn't be the one DIRECTLY doing the damage.
I say directly because I now believe it is a friends responsibility to do everything possible to make sure that friend does not drive impaired.
If anyone should happen to slip please do not drink and drive and do everything in ypour power to make sure your imbibing friends do not drink and drive.
Glad you got so much out of it. Peace.