I doubt it's much help but many people have them. Some, I suppose, are able to quickly put them aside, learn, and move on. Some are dwellers, who continually return to the regrets and wonder "what if". I suppose there's a middle ground of people who kick themselves for a while, then eventually get over it.

I suppose if the first group truly learns, then that's good. Though I think many who put aside their regrets quickly fail to learn from them. Maybe they can put them aside so easily because they keep regretting pissing on the electric fence, as it were.

Learning is the important thing. I don't know if you can choose not to be a dweller, I know I'm a dweller and it's difficult to even consciously stop myself. I will suddenly find myself dwelling on some long past mistake, miscue, or missed opportunity. So I know telling you to "try not to dwell on it" is pretty pointless.

So you've learned from your past mistake. Now the trick is to keep the lesson with you for the next time opportunity arises.
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Get over it.