I sinned some years ago, and I don't feel guilt about it anymore. But the one I sinned with, I have a hard time letting go. Please pray I can feel closure from God.
Sometimes it can very hard to let go of a previous relationship especially if that relationship involved physical intimacy. This was a stumbling block for me for some time after salvation seeing as I am single.
Here's the thing. I used to think it was because I felt lonely that I had elevated this past relationship to the status of an idol in my life. I felt that if God would only allow me to meet someone new that the problem would solve itself. Often times I would get frustrated not only with myself for stumbling but also with God for allowing me to be alone. I could not have been more wrong.
My problem was not a lack of relationship with another person. Instead it was a lack of personal relationship with God. The reason why I was stumbling was because I no longer valued God as my most prized possession. I had allowed other things steal my affections away from God thus I desired them more then I desired Him and because of this I couldn't keep myself from stumbling.
That's when the realization hit me that I can't do this on my own. So I determined to turn my undivided attention toward God until I got an answer and God was / is faithful to give me one. God poured His grace out on me so thick that I could literally feel His presence. He told me that He never intended for me to face my troubles alone, that's exactly why He has given us the Holy Spirit to lead us and teach us His ways and that the Holy Spirit is always near when I need Him, especially in my moment of temptation. I then understood how reliant we are on God for everything and how He will never turn away just as long as we turn to Him whole heartedly.
That's when God won me over once again. My heart now belongs to Him and I have yet to stumble since. Now, that doesn't mean I haven't been tempted however, when that temptation arises I am reminded of the last time allowed something to steal my affections and what a wedge it become between me and God. Then I am reminded of how He never left me nor forsook me during that terrible time and how He is with me even right now. I turn to Him and fellowship with Him, turning my affections toward him and the temptation goes away.
When Christ becomes our most prized possession, sin loses it's hold on our heart.