I don't understand!! What difference does it make to your friend whether you drink or not. You are the same person you just don't drink. Where is the problem? I went out Saturday and my mates were delighted I wasn't drinking as it meant I was their taxi for the night! They just did exactly the same as on previous nights and probably got their hangovers to prove it! You have to do what is right for you and I am sure the majority of friends would respect you for it. All the best