Sounds like the alcohol played a role as to "why would you do that". Really there is no reason to feel prolonged shame... just manage the contributing factors that you can. I don't drink anymore myself because every time I do, I don't have enough fingers to count the things I regretted doing the night before while drunk. My major problem was not getting drunk in itself, but getting TOO drunk much of the time. Sigh. When drinking with people I was always the one going a bit overboard... And occasionally way overboard. The result was having regrets for way to long instead of just quitting.