Stumbling

If you are sincere about your walk in the light, without distractions like porn, you have to understand that the Devil will be sincere about causing you to stumble, i.e. to have further occurrences of sin in your life.

He will try to provoke your flesh against you. And sometimes, he will prevail over you.

Understand that your way toward perfect purity and holiness will (most likely) not be completed in this lifetime. But God will free you, if you are willing, from wilful disobedience and a constant walk in darkness. If you fall from grace, as they say, He will be strong to lift you up again.

My dear children, I write this to you so that you will not sin. But if anybody does sin, we have one who speaks to the Father in our defense - Jesus Christ, the Righteous One.
(1 John 2:1, NIV)

Ellen G. White, a Christian author of the 19th century, writes:

"You desire to give yourself to Him, but you are weak in moral power, in slavery to doubt, and controlled by the habits of your life of sin. [ ] The knowledge of your broken promises and forfeited pledges weakens your confidence in your own sincerity, and causes you to feel that God cannot accept you; but you need not despair. [ ] By yielding up your will to Christ, you ally yourself with the power that is above all principalities and powers."
(E.G. White, Steps to Christ, 47.1; 48.1)