I wasn't my best self
You're human. So is everyone. Part of being human is making mistakes.
We say things that are hurtful, do things that are insensitive, and can be careless in our relationships.
Making mistakes are human. Not admitting them makes things worse. It leaves open wounds to fester. But admitting mistakes can be so hard.
The best way I've found to admit mistakes is with one simple phrase: "I wasn't my best self."