Um, I'm not so sure I'd suggest Al-Anon at this very moment for your husband--let the dust settle from this shock, first.
First things first. It's great that you are going to a meeting tomorrow. Every single one of us was scared and nervous for that first meeting. It's OK to be scared and nervous. I do suggest you let people at the meeting know it's your first meeting. They will probably give you some phone numbers (the women will) so you can call people for support in between the meetings.
Listen to what the people at the meeting have to share. Every one of them felt lower than low when they came in for the first time. With recovery, they have happy lives again--even people who have done far worse things than you while under the influence. Listen to their stories and see how you are alike, not how you are different. We are all a little bit different inside and have had different experiences, but we share a common problem and a common solution.
Take things with your husband a day at a time. You both need some time and space to process what happened. Whether it spells the end of your marriage only time will tell. It does no good to try to figure out how it will all play out right now. The first thing is to get the alcohol out of your system and to start your own recovery--regardless whether he stays or leaves, you still have to live with you.
You can DO this. Lots of us have. We are no better people than you are, and you are just as deserving of a happy life as any of us.
Big hugs of encouragement.