What is the expiation required from a girl who committed an error and became pregnant out of wedlock, then her pregnancy was aborted, and then she repented to Allah, and is it obligatory for her to inform whoever proposes to her about what happened?

Adultery is one of the most heinous sins, and if it results in pregnancy and abortion after the ensoulment of the fetus, the sin is even greater. However, Allah accepts repentance, which involves abandoning the sin, regretting it, and resolving never to return to it, while concealing one's sin. As for abortion, if the woman herself performed it, she is liable for the blood money (diyah). If someone else performed it on her, he is liable for the blood money, and she must repent. She is not obligated to inform her prospective husband of what occurred, unless the husband stipulates her virginity, in which case she is not permitted to conceal its loss, without informing him of the reason.