Does the repentance of one who has cursed Allah, His Messenger, people, and everything else, get accepted, and is what he did considered an act of disbelief that necessitates killing himself?

Indeed, the sin you committed is the ugliest and greatest of all, but your repentance is undoubtedly accepted. Allah Almighty invites Christians to repent from their claim that He has a son, despite its enormity, as stated in His saying: (The heavens almost rupture therefrom and the earth splits open and the mountains collapse in devastation That they attribute to the Most Merciful a son). The Prophet, peace be upon him, emphasized that the statement "I have a son" is an insult to Allah. Nevertheless, Allah Almighty calls for repentance and forgives all sins, as He says: (Will they not then turn to Allah in repentance and ask His forgiveness? And Allah is Forgiving and Merciful), and His saying: (Say, "O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins"). And in the Hadith Qudsi: "If you were to come to Me with sins the size of the earth, and then met Me without associating anything with Me, I would come to you with forgiveness the size of it." Allah has promised those who repent from disbelief, murder, and fornication acceptance and the changing of their evil deeds into good deeds. Despairing of Allah's mercy is the most dangerous thing, so hasten to repent and have good expectations of Allah, for He is the Generous, the Loving, the Merciful.