Should i forgive her or no?

So the ex of my gf sents me screen shots of what my gf is sending her and it really looked liked she still has feelings for her. I told my gf about it we had a huge fight then she explained why she was talking to her the way she did. She told me its because she's still feeling guilty for sleeping with her friend after they broke up and she wanted to tell her anything for her to forgive her. But when i asked her if she still has feelings for her she told me yes but she doesn't wanna b with her, she wants to be with me. Honestly i don't know like am so confused. Help!