What is the Quranic, psychological, and Islamic interpretation and ruling regarding a person's state of extreme fear, frustration, and regret, especially after a specific event, and their intense feeling of guilt concerning certain forbidden acts?

Fear and anxiety are often caused by sin and transgression, as Imam Ibn al-Qayyim mentioned. Disobedience instills terror and fear in the heart of the transgressor, while obedience is a fortress that provides security. Therefore, sincere repentance and returning to Allah are advised, because Allah has promised security and guidance to the believers who have not mixed their faith with injustice. By rectifying one's relationship with his Lord, his fears of death vanish, and he realizes that this worldly life is a cultivating ground for the Hereafter, thus he rejoices in the fruits of his good deeds.