What is the way to repent from the addiction to pornography, incest, and cuckoldry, and to get rid of the fear of this addiction returning in the future and its impact on marital life?

These abominable acts are dangerous and have severe consequences in this world and the hereafter. What you fear may indeed happen due to the addiction to watching incestuous perversions. Do not hesitate to repent again, and do not despair of Allah's mercy, for Allah accepts the repentance of whoever turns to Him sincerely. What is required of you is to make a firm resolve and be truthful with your Lord. Among what aids you in repentance is frequent supplication and humble entreaty to Allah, for Allah is the one who enables His servant to repent, thereby guiding him to it. Allah's acceptance of repentance is of two types: permission and divine enablement, and acceptance and sustenance. Be diligent in seeking means of assistance to remain steadfast upon the truth and to tread the path of rectitude, and to safeguard yourself from Satan and his temptation.