penitent - sorry
A ‘penitent’ person is highly remorseful and apologetic for past sins or transgressions. Implied in this formal word is also the resolution not to offend in such a way again. The term was originally used in a religious context to express seeking forgiveness from God, but has since branched out from that specialization to become more general. Most commonly encountered in written English.
Initially, I was furious with Andrea for what she'd done, but she looked so penitent that I decided to forgive her.
The parole board were highly sceptical about the prisoner’s penitence. They felt he was putting on an act so that he could be released early.
After the scandal, the celebrity made a penitential plea for forgiveness that included accepting responsibility and resolving to do better.