Charged last summer on a felony charge I didn't know was illegal.

Last summer a male friend and I got into a argument and told me to hit him ,which I did. I know it was wrong. Unfortunately it caused a very small laceration but bled alot. He called the cops on me, and on my way to work I was arrested for simple assault. When the police searched my car they found an empty vial of Ativan in the console that had been there for months. I work as a RN and had given the last dose to resident that was dying and very restless. After giving the medication I put the empty vial in my lab jacket and continued with my cares. On my was home I realized it was in there and placed in the console so I could lock it until I was able to dispense it correctly because I have 11 year old at home. Needless to say I forgot about it, like I said it was empy The count has always been on and no ativan has ever been reported missing. My drug screen was negative, the police searched for needle marks and could not find any. I have a lawyer and the states attourney told him they wanted to question me about a robbery of a pharmacy in the town where I live. They seem to think I know something about it.I dont even know what day it happened on! I have already been question by the DCI a while back. I'm thinking they think the friend I hit had something to do with it, at least thats what they said ( trust me he's not smart enough) he once stole a pint of vodka, then wet him self he was so scared. what can I expect? any advice? and what about my Nursing Lisence?