Some criticism is sandpaper. Uncomfortable, but look how much smoother the work got.

Not all criticism is sandpaper. Some of it is just someone in a bad mood with an audience, and you are allowed to put that down. The useful kind is specific, aimed at the work rather than at you, and annoyingly accurate. It stings, and a week later the thing you made is visibly better.

Sort the next feedback into one of those two piles: does it name something you can actually change. If it did, use it and tell the person it helped. If it did not, you have not failed a test, you have just met someone with an opinion.