I've never been so humiliated and sad at the same time

I went inside the shop to buy milk and forgot I had purity inside my bag, i was quick as I was late for my babies appointment, on my way out the security asked for the receipt of the purity I didn't have it she immediately said I stole the purity, I asked for the camera she laughed, the manager didn't intervene said he does deal with security staff, they are continuing with their duties and let me me standing missing my son's appointment, management intervene please