Most people get defensive when they're criticised and people who drink are probably the worst. I know I was like that.
I have been accused of being 'high and mighty' already by my drinking family, even though I haven't once criticised them myself. Because you are doing things right they are going to see your very presence as a criticism. It's their problem not yours.
It's sad to say but if they are not being supportive of your decision to not drink and have gone so far to end your relationship then I would be inclined to not contact them at all. Given time hopefully she'll come to her senses. Obviously driving under the influence is a stupid thing to do and you were right to point it out. Gain strength in the knowledge that you did the right thing.
I'm sorry you are hurting but I hope you won't burden any of the blame in this situation. *hugs* x