Sorry you slipped up and feel down. It's especially sad since you drank because you were in a good mood and celebrating! I did that all the time too. Don't beat yourself up. I agree that the family relationships will seem clearer when you're sober. But perhaps you also need to tell more people you are sober so they don't "treat" you to something so tempting next time? Just a thought
But the good news is you are here posting already. You'll get it next time!