Not a woman, but a some teenager girls I met in high school were absolutely vicious.

Usually, they say it, but not directly to you. The attacking woman will tell another person in the group, and that person will usually tell the target woman what was said by the first woman just "because I thought you should know." Very, very rarely is it said directly.

I also have seen a lot of people pull the move of talking too loud about things they hate about the target woman on purpose so that the target woman hears it, but can't really confont the attacking woman because she "should mind her own business."

From what I hear it's usually more about back-handed compliments than outright insults, like "wow, you must have a lot of confidence in yourself to wear that, go you!"