Your cry for mercy lands on a God who delights in giving it. Mercy is exactly what you need and exactly what He promises, not the wages you deserve, but a full pardon. When you say, “Have mercy on me,” you are taking the only posture that opens the door to cleansing. He has never turned away a heart that confesses its guilt and clings to His kindness.
That guilt feels heavy because the sin has been living in the shadows. Pornography thrives in hiding, but you cannot hide it from yourself. It sits there, ever before you, draining your peace. As long as we try to justify or minimize a sin, forgiveness cannot do its freeing work. Healing begins when we stop covering and start naming it for what it is. You have done that here. Now let that confession run its full course: agree with God that it is sin, and trust that His desire is not to crush you but to restore you.
The ground of your forgiveness stands outside of your performance. Jesus, who knew no sin, was made sin for you. Look at the cross. He took what you deserve so that you could receive what only He deserves, righteousness, cleansing, a clean record before the Father. That is where your guilt is removed. But there is more. When you see yourself crucified with Christ, the power of this addiction is also broken. Your old self, the one enslaved to lust and fantasy, was put to death with Him. A dead man cannot be enticed. So the hold pornography has had over you is not the last word. Sin shall not have dominion over you, because you are not under law's condemnation but under grace's liberating reign.
You asked not only for forgiveness but for healing, to have the sin taken away. That is the work of Jesus as your great High Priest. He not only atones for guilt; He separates you from the sin itself. He has made provision to break the cycle. When the pull comes again, you do not have to yield your body as an instrument of unrighteousness. You have been set free. Come boldly to the throne of grace right at that moment, not just later in shame, and you will find mercy already waiting and grace that gives timely help.
The heavy hand of guilt you feel now will lift. There is a blessed happiness reserved for the one whose transgression is forgiven, whose sin is covered, to whom the Lord does not impute iniquity. That can be your song in the morning. Let the redeemed of the Lord declare His mercy, for it endures forever. Your cry has been heard. Walk forward as one cleansed and empowered, not as a slave who must fall again, but as a person whose old master has no more jurisdiction over a life now hidden with Christ.