The self-crit

Self-crit is the part of apologizing that people frequently ignore--and it's the only part of the apology that makes it meaningful. A great line from season 3 of Bojack Horseman is when Todd finally calls Bojack on all his shit: "You can't keep doing shitty things, and then feel bad about yourself like that makes it okay!"

A self-crit means you say what you did wrong, and why it was harmful. No explanations. No excuses. Nothing about how you feel.

This is the only way to demonstrate that you understand the problem enough to be better in the future. They know that you know better, so hopefully you won't give yourself an excuse to do it again.