Innocence and naivety are not the same things.
Your innocence is not wounded when you witness evil, nor when you suffer it; what you lose is your naivety about evil.
But it is when you commit evil that you scar your innocence. Even if you repent and are forgiven, you do not forget; and you will forever miss the unscarred beauty of your innocence, even if those scars are concealed in places no one can see.