It's time to tell my parents about AA and my sobriety. I am scared shitless but oddly excited. How much about my past do I tell them?

My parents are visiting my sister this coming weekend for a sorority event, which means heavy drinking. I feel like I need to tell them ASAP so that they can have some time to digest, ask questions, maybe hit up an Al Anon meeting. My family is fantastic, I was raised very well, wouldn't change a thing, I am just fucked up and have finally accepted that.

I'm guessing they will question my decision and try to tell me I am not an alcoholic (unless I haven't hidden it as well as I believe I have) but will accept my decision. I'm wondering how much I should share once they start asking questions. My mom is a worrier, which is why I have not told them to this point.

Do I admit to the drunk driving, blackouts, random sex, etc? If not, how do I get the point across that I am an alcoholic and need to do this without going into specifics? Do I suggest Al Anon? Should this be an email so that we both have time to think about what we are going to say, or should I try to Skype with them, or just wait till them get here on Friday?

I'm 27 and female if that matters.