This is a very very close to the heart topic for me, it almost scared me reading it.

I'll probably have some input tomorrow.

In the meantime I like SeptMorn's idea about stopping her when she tries to tell you gossip. I think you can do so without being antagonizing, you don't have to explicitly criticize her for gossiping, just say that you don't appreciate it, and let her "take the hint" that it might be a subtle insult.

If she is close to the chief though be careful. If I have the stamina I'll relate my story again.