Underage Possession of Alcohol

My question involves criminal law for the state of: Virginia, City of Norfolk

i need help getting out of an underage possession of alcohol charge, got confronted walking out of a gas station by an undercover police officer who worked for ABC and he asked my age and i gave him the only id i had which was my brother's passport, which is what i used to buy the alcohol then he started asking questions and he treatened to give me a federal charge of identity theft if i were to be caught lying so i busted out and told the truth. what should i do in court to get the least punishment?

also i was not driving and i was not drinking beforehand

You should consult a local lawyer about local sentencing practices. The outcome will depend upon that along with your age, prior record, and the full facts of the incident.