What can I do if charged with unauthorized use of a motor vehicle?

I borrowed a vehicle from a friend. Come to find out the vehicle I borrowed was still in her ex-husbands name. He happens to be a police officer and saw me driving the vehicle. He had someone else call in the vehicle as stolen. I was stopped by police at gunpoint and handcuffed and taken away in a police car. The charges were lowered to unauthorized use of a motor vehicle. This vehicle is supposed to be the property of my friend and the papers are sitting on the judges desk at this moment. What kind of case does he or I have?