Forgiveness can be a great thing. Letting go of the past, wiping the slate clean. Getting a fresh start.
You shouldn’t hold on to bad experiences like this if you really don’t have a reason to. I mean, if it was actually traumatic, then you should be working it out with your therapist, they’d be the best person to ask here.
But if all it is is bad feelings, then you won’t just be doing her a favor here. You’ll also be doing yourself one.