I forgive my ex but she doesn't forgive me, why am i okay with it?

My ex manipulated me 19m alot and was really childish and used me for money and attention. She 18f had poor communication skills, i tried to help her improve them and each time it was avioded. Today i went to her house just to see if i left some jeans there, she Didn't. When i was leaving she said "i don't forgive you and i never will" i told her that's okay, i feel good that i have the power to change and forgive.Its hard so see that she cant change ,i just hope she will one day not for me but for herself.