How can one repent from falling into polytheism (shirk), how can one rectify injustices committed against others, how can one free themselves from attachment to a person that led to sins, and what is the way to deal with feelings of sadness and distress that follow the severing of a relationship?

Repentance is achieved by regretting sins, abandoning them, and resolving not to return to them. If the sins pertain to the rights of people, then restitution must be made to them or their forgiveness sought. Shirk (polytheism) is forgiven by Allah through sincere repentance.

Not filling the heart with the knowledge and love of Allah leads to attachment to creation and anxieties. The remembrance and love of Allah are the life and delight of the heart, and turning to other than Him is its ailment, while its cure is returning to Him. The questioner should compete in drawing closer to the Creator and winning His love and pleasure.

Regarding lying, slander, and reconciling disputes: In addition to the conditions of repentance, the questioner should retract their lie to their friend. As for those who were slandered, it is sufficient to pray for them, be good to them, speak well of them, and retract the slander to the listeners, without informing the slandered individuals to avoid fitna (strife). If repentance is sincere and effort is made towards reconciliation, it is hoped that Allah will not hold one accountable for what occurred.