It's difficult Alan I agree - but I knew that what was 'ok' for my mates was killing me - they'd all sober up and go to work or home to their family - I kept drinking....
Talking to them one on one, explaining my problem and my reasons helped - some of them got it, some of them didn't but they all supported me (even if some supported me by going away)
Talk to your Dad and your mates - tell them as much or as little as you like, but let them know you want to be a non drinker
D