This is the book that I bought the day after I started my journey to sobriety. It really helped me - it's not judgemental, it uses the term 'problem drinker', it's written by people who've been where you are now and where I've been too, and it's got lots of help and advice on different treatment options.
I wholeheartedly second Poshindevon's advice to get yourself to your GP. This is a very important step in breaking down the walls of secrecy and silence that surround our problem. It makes it real, at least within a confidential setting. Your GP will have seen it all before and should be able to advise on whether you need to have blood tests, or take supplements (I had to take folic acid although I can't remember why?).
For today and tomorrow, it's about not drinking, being kind to yourself (the recriminations and guilt are useless and more often than not just triggers to drink again 'to forget' or 'the damage is done now so I might as well carry on'). Start doing the work, start thinking about how you're going to change your routines to avoid drinking. If you need there to be no alcohol in the house for a period of time, say so.
Over the next few weeks, you'll need to start telling people that you have a problem with alcohol and you've given up drinking. This has two benefits - one is accountability (harder to hide if you're drinking again) and the other is that they should stop pestering you to have a drink. It will be best to avoid situations with alcohol as much as you can, this may be difficult two weeks before Christmas! But if it means not going out - well, just don't. Your health is more important.
I normally suggest people think about giving up for six months. One month is too short (although at least you will have company with people doing Sober January) and 'forever' seems too daunting to even get started. Six months is long enough to have made real lifestyle changes, got through some key events where normally drinking would be standard, to recognise some of your triggers (cooking dinner is always a good one) and to start to feel the benefits of not drinking.
I am six and a half years sober. I used to read posts like this on MN and think 'that could never be me, I could never manage to give up booze'. It turned out it could be me. Now it can be you. Good luck.