Right, I know this guy is your friend but if he treats people that way then he's obviously an asshole. By the same note, if he treated this girl in that way even after he knew you had feelings for her then he isn't worth your friendship. As for the girl in question, you need to talk to her face to face and confront this head on, all or nothing. If she isn't returning your calls then trying a soft approach obviously won't work. You need to find her, say visit her at home or work or try and arrange to meet up, and tell her exactly how you feel and sort things out now. If you don't then things will just get worse between the two of you, and your friend. It sounds hard but believe me, it'll be better in the long run.