I blocked my ex on Facebook while she was still living with me. I knew that she
stalked me checked my profile through one of her brothers sometimes. I deactivated that account a little over a year ago for reasons unrelated to her. I made a new one under our kids' names. We have only one mutual friend, her one brother that I like. She sent me a friend request a month ago. I ignored it. She's never mentioned it, and I certainly won't. That's a boundary, and boundaries are about us, not controlling the other person. Boundaries are about aligning axons with our core values (
see here for more).
It's bothering you that she is following you. What do you feel makes you more comfortable: ignoring it, or blocking? One boundary is internal, the other external. This isn't about her, but you.  :)o you really feel that she might escalate? You could let it ride for a few months, then block.