How to forgive daughters mother.?

Tired of fighting with daughters mother. She had done a lot of bad things to me but the worst was I had to take a paternity test so my name can be put on the birth certificate. Found out im not biological father. Daughter mother lied to me again, this is the worst thing I had to struggle with. Since i already agreed through temporary custody hearings she was my daughter there is no problem with legalities. And she is my daughter regardless. I love her very much, as for the mother she is more angry at me because I showed result of test to her family and she says its bogus, but a 99% excluded pretty accurate. Her family admires me for what i done, But how do I forgive the mother I want to in my heart, but in my gut there is a lot of hurt. My pastor said but you in her shoes, life cant be good to her right now. My daughter means the world to me, and I focus a lot on that. How can I make things better, so this hurt goes away, how do I forgive her