A giant apology post fixes nothing. A hundred quiet days of being different fixes a lot.

A public apology is mostly addressed to the audience rather than the person harmed. It produces a feeling of resolution for everyone watching, and it asks the injured party to accept a performance as repair. What actually mends anything is unglamorous and slow, and almost nobody sees it happen.

If you owe someone, say it to them directly and briefly, then behave differently for a long stretch. Do not check whether it is being noticed, since that turns the repair back into a performance. The proof is in the ordinary days, and they count most when you were not counting them.