I've spent years learning to negotiate the relationship with my father who drinks too much. I would call him an alcoholic, but the rest of the family don't, in Ireland I think acceptable levels of alcohol are somewhat different to the rest of the world...
I spent years agonising and feeling guilty when I didn't respond to his emotional requests / demands (eg. phoning drunk at midnight often midweek, and accusing me of being 'BORING' when I said I was asleep, saying I didn't call / visit enough, accusingly tell me that I was so much like my 'mother' - insert spit and venom here). I went to Al-anon, AA for families and friends of alcoholics and after a few years I feel like I have made huge progress. Our relationship was not as difficult as many of you describe and different in many ways so I'm not suggesting that I have the answer. But - in my experience, setting out clear boundaries worked, but not in the form of 'I'm setting boundaries here because I find our relationship difficult'. Rather it was 'you cannot call me at midnight drunk anymore, you cannot announce that you are visiting me at 1 days' notice and expect me to be happy about this', etc. I enforced it diligently for a while and then he stopped doing these annoying things. This is just an example. I also resolved to stop feeling guilty, trying to fix him, trying to pander to him, etc. I found this group enormously helpful. Interestingly enough, we now have a good relationship (most of the time).
For those who feel guilty, struggle to set boundaries, look after yourself, etc, you might find the X-anonymous groups helpful (you don't need to be religious contrary to popular belief (I'm not), but it is not for everyone, so I am not trying to preach or proselytise!). Coda = dependents anonymous is really good. Websites might have some useful tips and info.
Good luck & take care!