This is a very important point (it was also mentioned by post #844) - I agree, she didn't call her brother for help because she was disorientated and feeling bad - while Diane was outside the car, Emma took her aunt's phone and called her father. When Diane was getting back into the car, Emma broke off the call. Then Diane's brother called her back to talk to Diane - maybe he didn't mention Emma calling (to make matters worse). She did not ask for help because she did not feel good.
My Opinion: She was a functioning alcoholic and no one knew. After the fact, people close to her will start putting 2 and 2 together and start thinking about her behavior over the past few years -- then they will see the pattern. In order for her to drink that much in such a short time and not be an alcholic, she would of been very physically sick. Functioning alcholics need some alc0hol just to act "normal" -- then they drink more (because they want to or can't stop) and become drunk.
I agree that once she got on Taconic, she "hunkered" down and focused on driving in what she thought was the slow lane.
I agree that if her husband thought she would drink on the way home (or was drunk) he would not have let her drive with any of the kids in the car with her.
It will be interesting to see what becomes of this case. I appreciate all the input, questions, and discussion.