She can only behave in this way because you allow her too.
You say that you do not show how she affects you but I bet she can see exactly how she has affected you, unless you're a lot better actor than the rest of the world.
Of course she is currently feeling giddy, you allowed her to win again! by letting her get away with not signing the addendum that every-one else has signed.
If you're waiting for things to get worse then they will, people usually get what they think will happen, that's why you should focus on what you want to happen, not on what you do not want to happen.
You've worked with her for seven years, I get the feeling that you need this. As I said before she can only affect you if you allow her too.
You're the boss, she is a pain, show her the door! or do you need this situation more than you're willing to admit.
Or make her the boss as she clearly runs things anyway, and be happy as the subordinate co-worker.
Not very eloquent, but potent.
({{{<reiki hug>}}})
John.
