I'm having issues with my best friend...what should i do?

Well, we have been best friends for over two years. hes male and im female. The other day i heard that his girlfried hated me and doesnt trust me. this girl doesnt know me at all. i have tried to talk to her over four times about how jeff (Thats my best friend) and i only have a platonic relationship. after i heard about what she was saying aboutme i felt that i had to tell jeff. they were having issues because of me and i was going to talk her again but when i heards about what she said i told him i couldnt and i told im what she said. the next day he told me that she had broken up with him and she wouldnt get back together with him unless he stops being my friend. thats all i really know right now becasue jeff hasnt really talked to me about it. i can tell that he is very upset about it and im worried. Im worried for him but i am also worried about our friendship. should i be?