Apostasy is not the solution, brother, the solution is sincere repentance and this compunction you feel is really a good sign. So do not let the Satan play with you to keep you away from Allah SWT.

Brother, never feel despaired of repentance. Allah (exalted is He) said, “Say, [O Prophet]: O My servants! Those [of you] who have committed [sins in great] excess against their own souls, never despond of the mercy of God! For, indeed, God forgives sins, one and all. Indeed, it is He [alone] who is the All-Forgiving, the Mercy-Giving.” [39:53]

Out of His grace, Allah, the All-Merciful, has opened the gate of repentance wide for all those who repent sincerely and earnestly to Him no matter how grave their sins are. Part of this repentance is to quit all the practices that stimulate your desire, such as gazing at members of the same or opposite sex, watching explicit contents, etc. Reading and writing erotic contents is absolutely prohibited and there is no disagreement among scholars in this regard.

You need also to keep your time busy with useful activities, because leisure time is a big opportunity for the Satan to incite you for evil acts. Attend congregational prayers, find religious friends, stay away from the internet as far as possible, try to memorize the Quran, try to serve your community through philanthropic activities, etc. These are just examples of things that fill your time and keep you away from thinking about our appetite.

You did not say why you feel not ready for marriage. Marriage will most likely help you end this problem along with the abovementioned suggestions. Please rethink about it and have strong will to fight the Satan who still wins over you, though you are a muscleman.

Allah Almighty knows best.