P.S. I once invented a concept, and proudly did a presentation on it. It was rudely brought to my attention that this was well known in computer science. Very, very embarrassing.
Personally, I would not have bothered about their rudeness - although I know it's hard to totally ignore such comments.
I would be proud of myself, or at least be happy, for having invented the concept independently, more so if it was well known in computer science, because that indicates it had some utility.
Independent invention is a stronger data point than peer review, or even independent reproduction.
The phenomenon is so common in tech--something I, too, have experienced despite computer science having been my major--that it should practically just be a right of passage for software engineers.