Letting go of it is necessary to move forward. It doesn't mean you will forget about it. You will remember it so you can protect yourself from it ever happening again.
But at the same time you have to let it go to protect yourself from it. You can remember it without RELIVING it and letting it hurt you over and over again.
You may have had no choice when it happened to you but you do have a choice to not relive it so it can hurt you again. Once was enough.
It is through your experiences, both the good ones and the bad ones that are both a part of what made you who you are today. Your past doesn't define you but it is what you learned from it that made you who you are.
The wisdom that you learn on your life's journey will make you wise. Some life lessons are painful lessons and some of them are treasured memories.