I am a 22 year old guy and have been dating a lady for the past two years. Two days ago she notified me that she lost her virginity three years ago. To me this came as a deep shock in that I had trusted her and had asked her if she had had sex before, of which she answered no. I have forgiven her for her past mistake, but I find it difficult to forget. Please advise.
To forgive means that you have released another person from a debt that he owes you. If you owed, say a hospital, money that you cannot pay and had to file bankruptcy, a part of the process is a forgiveness of the debt. Would you want the hospital to repeatedly bring up the matter that you had owed them money after it was forgiven, or would you expect that the matter should be treated as if it had never happened? It is the later that is contained in the idea of forgiveness. "Indeed it was for my own peace that I had great bitterness; but You have lovingly delivered my soul from the pit of corruption, for You have cast all my sins behind Your back" (Isaiah 38:17). You can't erase your memory, but you can treat that memory as being no longer important.
I assume you thought you forgave her for not being a virgin. That is not the sin she committed against you. You weren't in her life at that time and she did not owe you anything. Her sexual sin was against herself and not you. "Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body" (I Corinthians 6:18).
What she did against you is lie about her past. Like many people, she assumed that if you knew the truth that you would leave her. Thus, she did not trust the strength of your love for her. That changed over time. She knew she had done wrong by lying to you and she did not want you to make a choice about her under false pretenses. She should never have lied, but we should recognize that it took courage to admit her sin, knowing it would lower herself in your eyes. I see that as a sign of the depth of her love for you. If you forgave her of anything, it should be that you forgave her of lying to you.
So the real question is: Can you let go of the fact that she lied to you? Can you accept that by admitting the truth that she is telling you that she loves you enough that she trusts you with her secret despair? And that she loves God even more because she is willing to lose you in order to please God? The lie was wrong, but the truth deserves respect.
Your assumption was pretty succint. I now appreciate what forgiveness means and know what exactly to forgive. And by the way, God's grace must very great to forgive sin including what I supposed to have been commited against me.
Thank you for your advice. It has really eased the tension in my mind. God bless you.