Sorry to hear you got wrapped up in the tidal wave again. I know how those nights always were. It really messes with your head when they throw their rhetoric at you.
I don't have a lot new to add other than what was said above, and to say what happens in your house today regarding AW drinking does not have any bearing on her childhood or your childhood. However A's are outstanding at finding ways to be able to throw the blame towards others (such as yourself, or those who raised them, etc) as a way to justify the drinking.
If the reason to be drunk is just "because", that's not acceptable in their mind. They have to be drinking for more than "because". So, that becomes things like:
I wasn't raised right
I had a rough childhood (how many years ago was that?)
You hound me about drinking and that makes me want to drink more (my favorite and one I got a lot)
If you didn't bring up drinking I wouldn't have drank, but because you asked me about it I'm drinking now
I had a really bad stressful day ( at work/home) etc today
I am celebrating (insert random event here)
And the list goes on.
But the key thing I think we need to keep reminding ourselves is this is a window inside their head, and I think they also believe this to be true, that they actually deserve drinks as rewards (getting drunk is like a personal reward) and that also, deserve drinks for adversity (your case above, the adversity being that they were not given a chance to properly develop as adults and are drinking out of immaturity).
We all know none of these are good reasons to drink alcohol, even really a reason to have a beer or a glass of wine -- to me, the idea of telling someone, you really stressed me out or made me mad, so I'm going to have a beer to help make that better, is preposterous.
But we have to remember we are dealing with minds that see the world and most specifically the consumption of alcohol as a mind-altering substance in a completely different way than we do.
Sorry you got stuck in it, rest assured, none of it your fault not even in the slightest.