[neilk]

You're paralyzed because you now believe that you are 'ahugefool'.

Step one would be to try to find some way out of that pattern of thinking. No wait - step zero is to not give yourself usernames like that.

If you're an ordinary human like the rest of us, your brain goes haywire with low-probability/high-consequence outcomes. You'll want to punish yourself in proportion to what you missed out on. But maybe you should consider evaluating yourself on what knowledge you had at the time?

I think you need to engage in some "accounting" of everything you did, with someone you trust, like a therapist or a person whose business advice you trust.

Maybe you can try cognitive-behavioral therapy, with a trained therapist. You start with your negative thoughts like "I'm a huge fool" and recursively break those down until you arrive at baseline observations and facts. If you're a programmer this highly rational mode of therapy may work well for you. You will almost certainly find that your negative conclusions about yourself aren't warranted.