Trad asked 4 years ago

As salam ahleykoum, once I made an injustice towards a friend. Then I repented and I told her about it, she was angry, but when I asked her forgiveness she said that she forgives me. I am not sure she really forgave me inside of her heart because few times after, when we were not friends anymore (no hard fellings) she started to talk on my back to people mentionning this injustice. What should I do? (this was many years ago)