You can't ever forget but the event can have a very different meaning.
The concept of forgiveness seems to be mostly misunderstood. The concept seems to be that if I forgive a violation that means the violator gets away with it. It also seems to mean that I have to forget that the violation ever occurred if I have fully forgiven. These concepts are completely incorrect.
Let's first understand what happens if we don't forgive. By not forgiving I put myself between the violator and God so He, like the gentleman He is, steps back and says, "You want to be God? Fine! How's that working for you?" We make ourselves the judge and jury and actually hinder the Righteous Judge from doing a better work than we ever could. The second thing unforgiveness does is it destroys us and the rest of our relationships for life because we become bitter, cynical and untrusting toward everyone. It's like a fish caught on a hook, holding onto the hook so everyone can see how mean the fisherman is. For goodness sake spit the hook out you foolish fish! You're going to die otherwise. Now you can see it for the fish, how about yourself?
So what is forgiveness? How does it look? How do I do it when I'm so hurt? Forgiveness is admitting the injury happened rather than denying it or trying to make excuses for the violator. Then turning the violator over to God to be the Judge and getting out of the way. Lastly reversing the attempt of Satan to spread his venom and control to you and sending forth God's Kingdom power to that very violator through prayer and even acts of kindness to them. Be sure to keep yourself from entrapment by the violator in this process. Then look for good that is being developed in your character through this painful time. You may need some help from a counselor to accomplish this step.
I use the writing of a bill to help me. I got this idea from the Lord's Prayer which says, "Forgive us our debts as we forgive our debtors." Also keep in mind that our being forgiven is affected by our forgiving according to this verse. So I write them a bill. So-and-so owed me and didn't pay. 1. Honor 2. Kindness 3. Protection 4. Love etc. This helps me to recognize what it really is that hurts and not to deny any of it. Then I take a red pen and write across the bill Paid In Full and give the bill to God to do with it what He wants to do. Then when Satan reminds me of the offense I say, "You're right that did happen but I gave that bill to God so go talk to Him about it." He will soon quit tormenting you with the memory. The last step that is very helpful follows writing out all of the offenses on the bill. Write down every emotion that offense brings up: the anger; worthlessness; hopelessness; fear; insecurity etc. Then ask Jesus what He would like to exchange with you for these emotions. Then quietly listen. Jesus will speak to your heart and when He does the emotions tied to this memory will completely change. You can't ever forget but the event can have a very different meaning for you that blesses rather than hurts you for the rest of your life if you will take this step. I have seen this happen again and again from some very deeply violating hurts. Jesus can really change the memory!