How can a woman who has repented of a grave major sin be sure that Allah has forgiven her, and how can she ensure that she will not return to that sin?

Major sins are grave transgressions, committed only by those weak in faith. However, Allah has opened the door of repentance for sinners; He accepts repentance, forgives sins, and transforms evil deeds into good deeds for whoever repents with sincere repentance. Repentance means remorse and a firm resolve not to return to the sin. Allah rejoices at the repentance of His servant. One must distance themselves from the causes of disobedience and bad company, and instead associate with righteous sisters. Furthermore, it is necessary to adhere to Allah's obligations, such as the hijab (definition), and cease from sins like lowering the gaze from what is forbidden and refraining from listening to prohibited musical instruments. One should also increase in reciting the Quran and remembering Allah, attend gatherings of knowledge, and listen to Islamic lectures.