First you are struggling with sexual sin. It is a powerful tool of the Adversary and our fallen flesh. I would probably say every person at some point in their lives struggle with lust and temptation. However this is not an excuse to succumb to this sin.
The Apostle Paul mentioned many sins believers in Christ should not be doing. However, he specified we must flee (run away from) sexual sin. He knew how powerful sexual sin can be. He spent a lot of time with the Corinthians.
1 Corinthians 6: NKJV
18 Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body. 19 Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own? 20 For you were bought at a price; therefore glorify God in your body and in your spirit, which are God’s.
In the road to recovery we do have believers once addicted to sexual sins including inappropriate contentography. We have those who continue to struggle. One member confessed he hated his addiction to inappropriate contentography. One day he just picked up all his DVDs, magazines and books and went out to the backyard fire pit and burn and melted it all in a heap and made a point to drive to the local garbage dump to complete the job. That was his way of showing God not only did he hate his sin, he would no longer feed it. Of course I'm not encouraging violating local arson laws, but perhaps a first step is to clean out your computer files, any other media and print material. Stop feeding the beast and flee from this sin.
Also remember God is bigger than any sin we have. There are no sins He cannot conquer in our lives. Again I say our lives as even as washed in the Blood of the Lamb Christians there will be temptations. Yet God will give us the means to escape temptation.
1 Corinthians 10 New King James Version (NKJV)
Moreover, brethren, I do not want you to be unaware that all our fathers were under the cloud, all passed through the sea, 2 all were baptized into Moses in the cloud and in the sea, 3 all ate the same spiritual food, 4 and all drank the same spiritual drink. For they drank of that spiritual Rock that followed them, and that Rock was Christ. 5 But with most of them God was not well pleased, for their bodies were scattered in the wilderness.
6 Now these things became our examples, to the intent that we should not lust after evil things as they also lusted. 7 And do not become idolaters as were some of them. As it is written, “The people sat down to eat and drink, and rose up to play.” 8 Nor let us commit sexual immorality, as some of them did, and in one day twenty-three thousand fell; 9 nor let us tempt Christ, as some of them also tempted, and were destroyed by serpents; 10 nor complain, as some of them also complained, and were destroyed by the destroyer. 11 Now all these things happened to them as examples, and they were written for our admonition, upon whom the ends of the ages have come.
12 Therefore let him who thinks he stands take heed lest he fall. 13 No temptation has overtaken you except such as is common to man; but God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will also make the way of escape, that you may be able to bear it.