I think the biggest mistake would be to think you have "lost" eight years of sobriety. You still have that experience and all its lessons. You slipped. This is only as big as you make it. There is a lot more that defines a person than whether or not they drank after a period of time. There are many people that drink every day or drink occassionally and you did no different on this one occasion than they do. You did nothing "wrong", only something potentially very harmful to you if you do not learn from it quickly and put the event behind and just keep on living a sober life. Slipping, is not a major catastrophe. It is what happens afterwards that makes the difference. Don't awfullize this event and make it something that leads you further down. There should be no feelings of failure. The drinking event is not a failure and does not define you.