I just got scammed and feel terrible

I was driving a motorbike in Bangkok, I'm an American tourist that was teaching yoga in Cambodia. I don't have my IDL. I stopped at a major intersection, and I was in the cross walk. Like everyone else Fricking does. A cop on a motorcycle pulls up to me, asks for my lisence, and drives to a traffic building in the center of the big intersection. Said my traffic violation itself was 4000 baht and driving without a lisence was 5000 baht. I new it was steep and I talked him down to just fining me 5000 baht for the lisence, and paid it. He didn't record anything, I couldn't take any pictures. I later realized it was a huge (?) inflated price. I turned around and arrived at the building 15 minutes later, and a traffic security guy said call the cops. The cop who pulled me over was in a dark brownish green uniform. Seemed official? What should I have done? Should I feel super dumb? I am really beating myself up over this.