My question involves criminal law for the state of: Washington

Recently I was driving with my cousin when he pulled off next to a car in a parking lot and said he wanted to check what was in the vehicle next to us, I told him not to do it but he proceeded anyways. As such I chose to remain uninvolved in the crime and remained in the passenger seat of our vehicle while he was going through the car next to us.

Only about 5-10 minutes after leaving the parking lot we were pulled over by an officer who then proceeded to tell me that the witness identified me as the one in the vehicle committing the crime. However both myself and my cousin were cited for "Vehicle Prowling II" and "Theft of less than $250". When we go to court my cousin has agreed to take full credit for the crime since I was not directly involved.

My question is: If he takes the blame and states that I was NOT involved what are the odds that I will be convicted considering that a witness identified me and not him? Also what kind of sentence would I be likely to receive if I were convicted? My criminal history is clean, the worst I have is speeding tickets. I believe this charge is a gross misdemeanor in my state.