My friend lied to me

So a girl in my school said really bad things about and my friend told me about all this .Now I am out of achool .After one year my friend meets that girl and didn't even say hi to her because she wronged me .I told her that I don't want you to break relationship with her because of me. You can talk to her .But she said that this is what friends do for each other and she did it because she wanted to .But I hear that they did actually talk when they met and she lied to me . All this happened when we are having a fight because she said some lie about me to another friend . I was thinking of forgiving her as she is saying she doesn't want to break her friendship with me bit now this happened .What should I do? Pls help me .I am really torn