Adding my comments.....don't go.
Wondering why you haven't addressed this til last minute, as it seems to have caused a whole lot of drama and angst for you. If you haven't got yet, however, it's still not too late to cancel.
To put too fine a point on it....I bet your good friend will be a lot more disappointed if you die of alcoholism than miss a birthday dinner.
Just sayin'.....this is your life we're talking about. At any costs, to any lengths. How much do you want to stay sober?