Well it sounds like she isn't a really good friend. There are three things that you can try to solve this. Try to ignore what she says, eventually she will stop saying these things. Or simply tell her that if she keeps acting like this, you can't be friends anymore. Lastly you can tell her that you don't care what she says about you or him. If you ignore her and keep your cool, be mature about everything. If you don't show any sign of it annoying you, then she will back off.