She seems very desperate to maintain some kind of contact with you. I don't think she is willing to accept that you don't want to be around her. She's in denial and probably can't see what she's doing wrong.

I wonder where she seems to get all of this information from regarding your movements?

It's a tough one and I don't envy you. You've been quite upfront with her and made it obvious where your standpoint is when you do bump into her when she miraculously shows up at venues you're at.

Seems for now that you're going to have to think of strategies to deal with her unwanted encounters when you're out doing what you're doing to so that you can still enjoy yourself and not be phased by the fact that she's lingering somewhere in the background.