Please do bring it up. Unlike most people who feel guilty, you are taking action to make the world a better place. Too often, guilt is a substitute for action. You are transforming a terrible experience into motivation to do something meaningful and useful. That was such a wise and important decision for your own growth as well as for the kids you are helping.
As for the forgiveness part: Please remember that you were only 7 years old at the time. I want you to look around the next time you are at a mall and spot the 7-year-olds. Look at how little and innocent they really are. Kids that age believe the grownups! They have to. They are dependent on the adults.
You were just like them — little, dependent, confused and scared. You knew something was wrong but you also thought you were powerless to stop a big person who was in control. You did what most little kids do: You looked for a way to feel less out of control so you blamed it on someone your own size. That felt more manageable.
It’s long past time for forgiving that little girl who was you. You would do the same for any other little girl who was scared, confused, and upset. Why won’t you do it for yourself?
Please take your letter and this response to your next session. You can continue doing your good work without the burden of unearned guilt for something that happened 27 years ago.
I wish you well.