Ignoranceisbliss,
I'm not an expert in this area, but I have had a lot of experience dealing with friends, family and loved ones with this problem.
You've shown the first step by humbly asking for guidance. You have a drinking problem; whether you attach the scarlet letter to it is irrelevant. Your ability to manage your life, at least during the week, is silently misleading you into thinking you got this covered. You don't. You may not be collecting DUIs or work related penalties, but it is almost a certainly that your liver and the rest of your body has already paid a heavy price.
Can you manage drinking at all? You say you have struggled for 20 years to control weekend binges but with no success. I believe it was Einstein who stated that continuing to do the same thing expecting different results is a definition of insanity, or something to that effect.
LisaRose is spot on (as usual). If you can limit your drinking to 1 - 2 drinks per day, try it. Even if you can your liver would probably ask you to stop completely. I doubt that you can to be honest. You need to stop drinking completely, IMHO. I doubt that a professional would tell you anything different.
I would suggest seeking professional help. Does your workplace have an employee assistance program? If so go immediately and find support. Good luck.