What should I do? Leave it , or sort it out ?

Ok . well i like a guy and i allowed my friend to tell him, he took it great since no girls really pay attention to him. we talk on msn but not really face to face because we're too 'shy'. but now things are going wrong .. the friend that i allowed to tell him that i like him, talks to him about me behind my back saying not nice things about me and now he's trying to avoid me although we were getting close. why do you think she's doing this ? she doesn't even like him and yet she saying things like 'when she talks about you, she over exaggerates her stories' < she tells my other friend what she says and Friend 'B' tells me all about it . i don't know what to do . is a lying friend better than a guy? or should i pick a date over a mate ? he looks at me strangely these days to , what can i say to him to tell him it's not true? its like she doesn't want us two to be together (not that we were).