The part that I don't understand is what made the "best friend" "slip" and tell everybody? Make sure you dont tell them your PIN number or something important like that!
At any rate, don't worry yourself with what other people think.. Most likely everyone but the seriously insecure people will forget all about it and those that do remember, just tell them you are TG and dating your best friend then the two of you will be in the same boat together :p
Oh yeah, dont take my advice! Well, except for the whole dont sweat it most people will forget about it thing.
DANA