Dumb (techincal) mistake from the past does not let me be happy

I feel down for many months and it's all related to something that happened more than three years ago already, with no consequences in my personal life. In fact, I did not even pay attention to it until it suddenly stroke me a couple of months back. Let's sum up. I always consider myself a relatively smart person. I studied a highly demanding degree and did quite well. The story itself happened the last year of my studies in the shared student flat I had with some friends, who I love a lot. One night, after many,many months using our gas stove for dinner, I fucked it up. For some reason I still do not understand and I will never understand, I over-thought a lot trying to close the stove (something that I did automatically every day until then). The system was slightly tricky but ofc no rocket science, and instead of closing the one I wanted to use, I opened them all and put them to the MINIMUM (hence I couldn't smell the gas at the time). Somehow I thought they were left open before (extremely stupid assumption). Instead of asking my flatmates, since I was doubting, I trusted my "instinct" (second extremely stupid move). For "maximum security" I closed the gas bottle that provides the stove with gas, since I thought it was safer (in case something was wrong with the stove, we would not be sleeping during the leak). But that was another stupid thing. If it had been opened we would have noticed faster. But it was closed and we didn't. One of my flatmates went after me to make his dinner and ofc opened the bottle and used only one section, without checking the other stoves' position (completely normal). He finished, closed his stove and let the bottle open. The gas leaked for a while out of the other 3. We were at that time chilling in the living room without noticing anything. I guess that around half an hour later, another flatmate came in and smelled the leak. He closed it and we let the gas go away. Absolutely nothing happened. At that time I even defended myself saying something that "I really tried to close them all" but there was no excuse, everything was wrong. The over-thinking, not asking my flatmates... everything. They didn't even get pissed. They were a bit surprised, complained but nothing afterwards. My studies came to an end, I left the flat but anyway we remain very good friends. But the thought of this series of stupid decisions I made that night, that could have potentially killed someone, stroke me a couple of months ago and does not go away. I know that we humans make mistakes, sometimes we throw stuff to the garbage when we want to put it into the fridge, sometimes people are killed because someone forgets to check a traffic light. I know, mistakes happen, but usually there is a factor that was not present in my situation. People do not pay attention and accidents occur. BUt I put ALL MY ATTENTION and it went completely wrong. I did not forget anything, I was not driving, there was no stress, no hurry, no pressure, no drug influence (which also makes people do really dumb things) and all the same I made a series of actions that not even a monkey would do, while I was fully focused. And that coming from a highly educated person! The key part here is... How can I trust myself any more? What do "education" and "learning" mean, when I could end up doing something like this? The feeling-guilt I have when I think about it is so strong that affects me mentally and physically. My mood changed and affected my way of thinking. For example, it's a fact that we spend some time criticizing other people actions even in a silly level, like "oh woah check this video of this person not being able to pass through a glass door" and we laugh a bit. I automatically think "well, it could have been worse, it could have been a person leaving the gas stove on when trying to close it carefully". I call it the "paradigm of the absolute empathic person". And even if we should not criticize as a main part of our lives, it's something that we need at some level. And I feel I lost the right to use it. I lost the right to say anything about anyone. I am the dumbest. And now I work in a highly demanding working environment in terms of intellectual exercise, and this thought does not help me much. I also think that it's affecting my health already, since I'm kind of worried-down all the time (stomach problems basically). I became a bit cynical and I'm asking myself "What's the point" all the time. I don't like it, but I don't know how to get rid of it. I talked to friends and family and the answer is quite similar ("How can you worry about something that had 0 consequences, and since then you have showed that you are a smart person, as you were before?") But somehow this does not change the conclusions or how I feel because of what I did. To sum up, due to all of this I explained before, I can't be as happy as I want, things don't produce me the happiness feeling I had before, and I want to change that. I also want to recover the attitude I had before: learning, progressing everyday, being hungry for "more". I hate this passive attitude.

Thanks for the motivating words! :) You anticipated to things I did but did not explain in the post! Like the list of top smartest people doing dumb mistakes. I already went through it and read about a thing called "Bias Blind Spot", which basically means that smart people tend to make this mistakes due to overconfidence or pride. The list and this fact made me feel better for a while, but I ended up again thinking that not even these people reach the level of stupidity I reached, just comparable to the "Darwin Awards". But yes, I know that there is no point on worrying about it since I can't change the past, and use it only as a learning lesson would make my life better. What about the critical judgement to others? This is maybe a deeper question, but also bothers me. Does anyone, who have make terrible mistakes, have the right to criticize any other person? (And now I mean in any level, from just having some fun -without being a jerk ofc- to professional advice)