Mike, it happens. I remember having over 7 months and thinking I was completely free of ever drinking again and then BAM! That switch flipped and my AV caught me off guard. It's been a battle since but each time I get back at it and try again. This time for me I have consequences other than my health at stake so I'm really working it. But it took me a few false starts to get here.
Stop drinking right now before it turns into a full blown relapse / bender, take a deep breath and get day 1 behind you again. Go over what happened this time to cause you to slip and adjust your plan accordingly. Turn this into a learning lesson and not something you beat yourself up with. It's a bump in the road but you can do this!