Is the loss in my business and the accumulated debts that I've suffered due to envy (Hasad), especially from my wife's sister's husband, who imitates me in everything? And is it possible that the cause of this is my committing adultery during university? And how can I remove envy and increase my provisions (rizq)?

To cure envy (hasad (definition)) and the evil eye ('ayn), one must mend their relationship with Allah through seeking forgiveness (istighfar) and repentance (tawbah (definition)). For indeed, tribulation does not descend except due to a sin, and it is not lifted except through repentance, as Allah Almighty said: "And whatever strikes you of disaster - it is because of what your hands have earned."

This is followed by replacing evil deeds with good deeds, and adhering to piety (taqwa (definition)) towards Allah in secret and in public. For whoever fears Allah, He undertakes to preserve and grant him victory over his enemy, as Allah Almighty said: "And whoever fears Allah - He will make for him a way out."

One must also frequently supplicate and show humility, and increase in acts of obedience such as prayer, remembrance (dhikr), and charity (sadaqah (definition)), as well as perform ruqyah (definition) shar'iyyah (Islamic incantation). These are beneficial treatments for envy and other tribulations.