If you betray someone but they never find out (you never did it again) are you a better person?

Back in 2017, I slept with my older brother's girlfriend. They aren't together anymore for other reasons. He never found out what we did and till this day doesn't know it.

I've accepted it was very low doing it to my own brother. If he knew then our brotherly bond wouldn't be the same again. If he doesn't know about it and I never did anything like that again to him nor any friend, would this make me a better person by now?

If you betray someone but they never find out (you never did it again) are you a better person?
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