We are told that we will face tribulations when we come to the Lord. Most Christians deal with one temptation or the other, and you are definitely not alone in your struggle : p
Take comfort that the temptation itself is in no way sinful. The Lord Himself was tempted in the desert, and He did not sin. We have already fallen to sin, of course. But that is why He gave His life for us.
The Lord knows your struggle, He has told us that He will not let us be tempted with more than we can handle. Sadly, we are told there are beings who seek to destroy us, and they do so by tempting us to sin against God. Knowing that they have come to steal kill and destroy, it only makes sense that they would tempt us relentlessly.
Know that the Lord is with you when you struggle, and that He knows whats happening to you. We both know that these urges are no more than sexual urges, and that they can be denied and ignored. Theyre definitely frustrating : p But they cause us no harm when we deny them. And even if we give in, they just come back again anyways.
Dont not fear that you are being tempted, or even that you have already fallen. If you are willing to repent, the Lord tells us He is willing to forgive. Continue reaching out to Him, and continue the good fight : p Dont let yourself believe that because temptation can be difficult, that its completely impossible to do. We may stumble sometimes, but we can always seek His mercy and continue trying. Dont let the enemy lead you to fear and anxiety over temptation.