Admitting you have failed is hard. And even after you have accepted it yourself and spoken it out openly its not easy to discuss about it. It's so easy to get defensive or only look at the good sides. At least publicly. On the other hand it's too easy to go through those negative things in your head and disregard the good things.
The balance is somewhere there in between. You need to admit not everything went as planned. But there is always something good never the less. At least you tried. There is no bigger failure than not trying. Or giving up after just one try.
Those failures are the best way to learn. It's a lot easier to avoid them the next time when you know what is possible. The worst thing is doing the same thing all over again and repeat your failures. It's the same thing with all that was good. If you don't carry those forward you just open a door for more failures.
The first things is to identify the good things as well as the bad ones. Then you need to focus preventing those bad things happening again. Only after that can you start improving all those good things.