I got blamed for something I swear didn’t happen.

Apparently I missed a important object and it was accidentally taken by a customer when it got stuck to the bottom of one of their items. I don’t remember that item being there, at all. The evidence they showed me is a very bad blurry video image. The company was kind about it and understood it was a mistake, letting me off with a warning, but I still feel guilty?
I’m second-guessing everything now and questioning my own memory, I KNOW that item wasn’t there, and if it was one of my co-workers would’ve alerted me. I’m very detail oriented and a very tidy person of my work station so being called for this and blamed for is frustrating. I’m feeling guilty over something I know didn’t happen, or at least I don’t remember happening?

I’ve always lived in presumption of guilt due to my ethnicity and background, being from a country that’s known for crime doesn’t help, I told my boss this wasn’t the first time happening and I’m worried they may have taken it the wrong way as well? I’m going crazy and overthinking everything. My boss was so kind about it and they’ve already moved on but for some reason I can’t. I was asked not to tell anyone In the company about it but my closest friends work with me so I can’t talk to them about this. But I need to get it out because I’m going nuts questioning my own memory and actions.