I am not going to engage in the talk of forgiveness as it relates to forgetting or remembering. To me that begins to follow the rabbit trail of attempting to justify the act of forgiveness.
But how do we see or use forgiveness. The act of forgiveness can be used as tool used to build upon our own armor, or it can be used as a weapon to cut some one else down. A transgression requires two people, the offended and the offender, but the act of forgiveness is given solely to the offended party.
From your description, it seems like you are able to "let go" if the act of forgiveness is acknowledge. If the offending party seeks your forgiveness, you are able to grant it and find absolution in a way. But forgiveness does not need to be a two way street. Remember, you are in control of your own forgiveness. If you do not forgive the offending party, then you have ceded your power to the offending party.
You said you need an approach. If you can understand the predicament of man and the weakness of the flesh, then you should be able to find the understanding and compassion to have mercy and forgiveness to protect your own peace. The act of forgiveness is about you protecting and maintaining your own armor from the fiery darts of Satan. If you wait upon the offending party to repent first, then you will find a hole in your armor for the enemy to target.
Forgiveness needs to be about your heart first, not the conscience of the offender.
Isaiah 43:25
I, even I, am he that blotteth out thy transgressions for mine own sake,
and will not remember thy sins.
If you follow the Lord, then let forgiveness be for your own sake.
Forgiveness is definitely about the other person also - which is why repentance is such an important factor. If God just forgave, just for His own sake, then He would have no reason to plead with us(the world) to accept this forgiveness. If it was just about Him, then He would do it and be done.
Rather, God does it for both to be reconciled. In Isaiah He is stating this in the way of letting them know its not just all about them, but its a desire for them to Him. Yes, God's forgiveness is for His own sake - but for ours also.
Isa 44:22
I have blotted out your transgressions like a cloud
and your sins like mist;
return to me, for I have redeemed you.
Forgiveness is about reconciliation. Its not about the offended well being - its about mutual well being. That's what we miss about forgiveness. We think its about us, or its just about them, and rarely do we consider it a way of uniting.
This is hard - who wants to be united with someone who does horrible things to you? All I know is its a Godly desire.
Mat 5:23-24
So if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there before the altar and go. First be reconciled to your brother, and then come and offer your gift.
Forgiveness can start with either the offended or the offender. However, when it starts, it should be completed.