Wow, I don't think I've seen a sitch like yours before. I think the only thing you can do is to to be nice. Include her in all of the decisions she wants in on, don't react to any of her verbal jousting. Smile a lot, even if you don't feel like it. It'll make you feel better and, eventually, it'll get her to think about what she's doing that hasn't been very nice. Smile, smile, smile.
