You know as well as anyone that you can't control her---but you can show her what is and isn't acceptable behavior.
Decades ago, I had a friend that drove more than one time when he was drunk(no, I wasn't present). And by some miracle, neither he nor others were hurt. But it could have been drastic. I remember telling my brother about this---which really hit home. When my brother was young, both he and a friend went out drunk, got in an accident, and his friend died. It was a terrible time in his life---and he was directly responsible.
Anyway, he told me if I was ever in a vehicle with my friend, and he was drunk, to punch him square in the face. Break his nose right then and there. He wouldn't be able to drive that way. My brother stated that he wished someone did that to him, before he took his friend's life.
Is that the right tactic? Probably not. But it would show what we are and are not tolerant of. Yes, she is your good friend, and she helped you in your dark days, and you can do the same. Show her by not accepting her behavior. Help show her the destruction that will ensue. Be supportive...in the way of helping her...but intolerant to poor behavior.
Lead that horse to water. Maybe she will take a drink....
2 boys-18 & 20(special needs)
Married 22yrs.(together 27yrs.)
All work and no play has just cost me my wife--Gary Puckett
D-Day: 9/18/09 D-Day#2: 2/19/10 The Marriage Killer: 6/6/11
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