Nice work Tumble.
You did what needed to be done. It's not always easy, I am right there with you. I've had to bow out of some really big social events, things with my friends. Worse yet, with my buddies my only excuse is "Sorry, I'm an alcoholic. I can't come to these things right now". With work, you have some easy outs. Use them. Glad you did.
As for your alone time, I can also identify. Perhaps near the end of your drinking days you drank so much alone because frankly, you had nothing else to do? I know that was the case for me. I'd also been jobless and girlfriend-less thanks in part to alcohol, so there really wasn't much left. Drinking always kept me busy though, even when I was alone. It was my only hobby by the end. Perhaps that's your story too?
My advice would be don't sweat the isolation too much right now. Don't overblow it and wail "I'm going to die aloooone!" - it won't be that way.
However, you're going to have to learn how to create a new sober social life. That's the trick. A little hint: start planning some breakfast/morning events, because that will be your bread & butter.