What is the way to get rid of intense, sudden anger that leads to disbelief (kufr), and how can one atone for the sins resulting from it?

One must be wary of anger, as it is the root of evils. It has various remedies, including legal ruqyah and visiting a psychiatrist when needed. If anger intentionally and deliberately leads to disbelief in Allah, this is an exit from the fold of Islam. One must repent, utter the two testimonies of faith (Shahadatayn), and avoid repeating such an act, for Allah says: "And whoever of you reverts from his religion [to disbelief] and dies while he is a disbeliever - then those have lost their deeds in this world and the Hereafter, and those are the companions of the Fire; they will abide therein eternally."

One must hasten to repent and have good expectations of Allah, for Allah forgives all sins, as Allah says: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'"

Furthermore, it is not permissible for a Muslim to establish a romantic relationship with a woman who is a stranger to him; this is forbidden and a means to corruption, and it must be severed. If he wishes to marry her, he should marry her through her guardian, for the Prophet, peace and blessings be upon him, said: "Nothing is seen for two who love one another like marriage." If marriage is not feasible, the relationship must be completely cut off.