Wrongfully Accused for "Theft"?

I have always done my groceries at publix, since I was a little girl. Last week, I went into publix and did my groceries as usual. I noticed I kept running into the same lady, but I didn't think anything of it. I pay for my groceries, and as I'm leaving, that same lady flashes a badge at me. She asked me to follow her and the manager into the manager's office. They sit me down and ask me if I forgot to pay for something, and I was really confused and answered NO. Then they started looking through my purse, and asked me about my daughter's Flinststone's vitamins and I told them they were mine. Then they pulled out (what I thought was) my allergy medicine and I said that it was mine until I was that it had never been opened! Then I thought to myself "oh crap." The problem is that I always carry my allergy medicine in my purse and I always put the small items by my purse in the front of the shopping cart. Big mistake because I must have pushed them in thinking they were mine! I would never do shoplift, my husband is a cop for goodness sake! I was so embarrassed because everyone was watching, and the staff was extremely rude to me. I JUST spent $150 on groceries, why would I steal a $5 allergy medicine?? So they sat me down and I signed some paperwork. The cops were NOT called thank god. They said the worst case scenario is that I have to pay $250. We don't HAVE $250 to spare! They said I would be receiving a letter from corporate, to call and let them know what happened. What happens now?? What are the laws in Florida, and how does it work? How do I show them it was an honest mistake?