Same thing started happening to me quite a few years ago - I was maybe 25 and still in college. I had spent the previouc couple of years visiting a "headache clinic" for my migraines and was using a lot of pain killers and sleeping pills - they really gave them out like candy. (Now I'm hearing all over the TV about all these people addicted to Vicodin - I think doctors have been way too liberal with those controlled substances). Anyway, I finally got to a point where it wasn't worth the payback anymore with the alcohol, and I was not a big drinker to begin with. I missed wine at first, but I had only been drinking since my early twenties, anyway, so it wasn't that hard to go back. I know you hear a lot about the health benefits of red wine, but truly, I'm pretty sure alcohol is essentially toxic to the body. The reason you feel like crap is because your overloaded liver is trying to remove a poison and it can't do the job. Sad, but true - it's a bitter pill to swallow.
I'm actually glad I was forced to give it up. It was a bit of crutch in a way, and I found myself using it occasionally as an escapist thing, or to loosen me up socially, stuff like that. Which isn't necessarily a bad thing, but it can be a slippery slope, and I needed to learn how to be centered and approach various life events - good and bad- without the aid of any mood-altering substances. Like I've never had tipsy/drunk sex with my current boyfriend of six years, which was an adjustment at first since I tend to be a little self-conscious in that department and alcohol really lifted a lot of those inhibitions for me in the past, but it turned out to be a good thing - it allowed me to be really present and upped the level of emotional intimacy. I think it's also a good idea to look at why you feel compelled to keep drinking, even though you know you'll get sick from it a good percentage of the time. Anyway, that's my 2 cents on the topic.