I’m really sorry you find yourself in this position. Not all narcissists follow the same pattern. Some discard their target. Others like this person, perhaps, can’t let go of the control. My guess is that she can’t stand it that you, not she, called it quits. To a narcissist, that is unacceptable. She’ll do whatever she can to make it clear to you that she is still in charge.
It’s unlikely that you can get her to stop making you uncomfortable. All you can do is try to get as far from her as you can. You say you can’t avoid her completely. Please reconsider whether that is so. If, in fact, you have to interact with her or be around her, you need to develop some emotional shields so she can’t get to you. Be careful. If you distance further, she may escalate. You may need help and support to manage this. A therapist can help you learn how to stay safe while you detach.
I wish you well.