Thank you. I do want to contact them but am worried about implicating myself further, especially if they pull up the CCTV footage and see that I did indeed keep things in my bag. Wouldn't want to get the police involved and get into more trouble.
I'm annoyed at how the manager treated me and threatened to call the police if I didn't just leave all my shopping with them. He said 'as far as I'm concerned, this is all ours.' I also have reason to believe that he was recording the conversation on his iPhone without my consent, as upon reflection he kept twiddling with his phone during the event. And I'm worried about what he will do with the photo he took of me.
Maybe I should just let it go and chalk it up to my stupidity but it's been playing on my mind a lot.