To send someone a card that says you are upset over your past actions is an example of apologize.
intransitive verb-·gized·, -·giz·ing
- to make an apology; acknowledge, and express regret for, a fault, wrong, etc.
- to make a formal defense in speech or writing
intransitive verba·pol·o·gized, a·pol·o·giz·ing, a·pol·o·giz·es
- To make excuse for or regretful acknowledgment of a fault or offense.
- To make a formal defense or justification in speech or writing.
(third-person singular simple present apologizes, present participle apologizing, simple past and past participle apologized)
- (intransitive) To make an apology or defense; to act as apologist.
- (intransitive, often followed by “for”) To make an apology or excuse; to acknowledge some fault or offense, with expression of regret for it, by way of amends
- My correspondent apologized for not answering my letter.
- (intransitive) To express regret that a certain event has occurred.
apology + -ize, from Ancient Greek απολογία (apología, “a speech in defense”), from απολογέομαι (apologéomai, “to speak in one’s defense”), from απόλογος (apólogos, “an account, story”), compound of απο- (apo-, “from, off”) and λόγος (lógos, “speech”).