While the ethics of your decision to edit your recordings are debatable, my personal opinion based on the information you’ve provided is that you’re probably being too hard on yourself.
My understanding is that when professionals make studio recordings, their “performances” are microengineered to near-perfection; after many “takes” on the same piece, the best passages may be melded and spliced into a product superior in all details to any individual attempt in its entirety.
Unless I’m hearing a recording of a live performance, I assume that a professional’s recording will have been tweaked or manipulated to some degree. That’s probably not the default assumption for an amateur’s recording, but you didn’t explicitly lie unless you represented that your effort was in fact recorded in real time and unedited. Otherwise, you omitted a detail that might be critical to some listeners in some situations (e.g., an audition, an entry in a competition, etc.) but would be of minimal importance or insignificant to others (e.g., a gift for Grandma, or an example that represents your true skills rather than how you mess up when that red dot is blinking).
The question for your conscience then is whether such a doctored recording actually does depict your proficiency. Were the tempo, accuracy and expressiveness really something you could achieve on a good day under optimal conditions? Or was that speculative, hypothetical wishful thinking? Did the recording you created showcase your pianistic ability—or display your technical skills as a user of audio-editing software?
By the way, I doubt that a genuinely amoral person would even give a thought to the questions you’ve raised. I admire your introspection and your candor in sharing this dilemma. If you conclude what you did was sufficiently wrong, resolve not to do it again (or, if you do, be totally upfront about it). I don’t think it’s necessary to confess your past actions, though, as no one seems to have been hurt by them; let it be water under the bridge, and stop beating yourself up over it.