Is supplicating for one's sister's ex-husband sufficient as expiation for having written offensive poems about him, in which his name was not explicitly or implicitly mentioned? And is it obligatory to destroy a collection of poems that includes those poems?

Backbiting people is forbidden, and the backbiter must seek forgiveness from the one he backbit; otherwise, retribution will be taken from him on the Day of Judgment. Either some of his good deeds will be taken, or some of the wronged person's bad deeds will be placed upon him. Some scholars mentioned that it is not obligatory to inform the backbited person of what happened, but rather it is sufficient to treat him kindly, ask for general forgiveness, supplicate for him, and seek Allah's forgiveness, citing the sayings of Ibn Taymiyyah, Ibn al-Qayyim, and al-Mardawi. As for poems, any offensive content they contain should be removed.