I forgive you..." And he said those words because he sensed that it was the only...

I forgive you..." And he said those words because he sensed that it was the only way to save his own heart, to stop it from breaking in two. Despereaux, reader, spoke those words to save himself.
...
And then the princess took a deep breath and put a hand on her heart.
I think, reader, that she was feeling the same thing that Despereaux had felt when he was faced with his father begging him for forgiveness. That is, Pea, was aware suddenly how fragile her heart was, how much darkness was inside it, fighting, always, with the light, but she knew what she must do to save her own heart.
And so, here are the words that the princess spoke to her enemy...
Forgiveness... is a a divine attribute and once it is given to those who have hurt you, your own heart begins to heal.