That's awesome, I believe running has saved my life, but lets keep this in perspective. Running by no means will keep you sober, it's easy to have that mentality, I know I did. Two years ago after completing my second marathon just 2 weeks later I was sitting in a detox after almost 6 months of sobriety. So never forget the fact that you can't drink.
And once you get past the simple step of completing the half-marathon, start putting some real training time in and you might be able to post some nice times. Just finishing isn't enough after you have done it a few times.
Try Googling Todd Crandell, he has 20 yrs of sobriety and attributes his success to doing Ironmans.
Good Luck!!