What odd and immature behavior on her part! Isn't she just a wiz at relationships. lol

I would say a simple and courteous hello to her to be the better person in my own mind.
And sometimes with folks like her, I might have a neutral but warm smile and hello on the outside, and in my head I would finish it off with more of my true thoughts that continue after the hello "...you may now return to your avoiding." Just for my own fun