What should I do, knowing that I have been threatened by a person to whom I sent my pictures before marriage, and he threatened to publish them, and I have repented, and I know who can delete them, but that will take longer than the specified deadline?

You are not permitted to send pictures to this young man again. Remind him of Allah's punishment, and supplicate frequently for Allah to ward off his evil, with supplications such as: "O Allah, we place You against their throats, and we seek refuge in You from their evils," and the supplication for well-being in this world and the Hereafter. If possible, delete the pictures from his device. If he carries out his threat and the pictures are not deleted, then use allusive denial regarding your relationship with him after repentance.