Is it right to charge me for petty theft if I didn't physically take anything?

My friend and I went to a grocery store that he currently worked at. I put some sushi in a different refrigerator and went out to his car. While I was at his car, he grabbed the sushi from the refrigerator and walked out and got caught stealing it 3 days later. Now the grocery store is trying to charge me and my friend $50 each. If I don't pay then they are taking me to court. I did eat the sushi which later that night gave me hives on my body because I turned out being allergic to sushi. Could I use that in my defense if I do go to court because there wasn't an allergy warning on the box of sushi? Last but not least, they did have sushi samples that proves on camera I did eat their sushi, but they can't prove I ate any of the sushi my friend took. Remember, this is about me proving I didn't take the sushi, me being allergic to sushi would just be a defense.