Is there a bonefide need for her to contact you?
If so can you need to get your manager involved but be proactive and come up with a couple of suggestions for arranging a fixed point of contact to resolve this business issue.
Possibly involving flexing your time, or hers, preferably both a little to meet in the middle. However ensuring that this contact point is a fixed point in time, and is a one off, or if it’s needed to be ongoing, it has a trial period and feedback to ensure its effective for both parties.
By specifically focusing on creating a solution to a business need, you keep the high ground, and ensure it moves away from this persons shrieking & wailing(!), and just wanting you at her beck and call, when you are clearly unavailable. That’s a really ineffective way to behave and shining a light on it, whilst being perfectly professional and focused on solutions, will hopefully put a stop to her
What exactly is she saying when she’s leaving you these unnerving messages? I can’t tell if this person is panicking about the business potentially failing (falling numbers etc), which is unfortunate, and not nice to get her second hand panic passed on to you. Is she trying to get an ‘all hands on deck’ type of response where she expects you to leap in to help in your time off because it is an emergency? If so, you need to be clear whether you personally can make a difference by being on call 24/7, or if it’s an emotional response she wants, a show of loyalty etc, but the actual work can actually wait until you’re working again?
Or is she actually threatening you with ‘soon to be unemployment’ if you do t pick up the call right then and there? Which is a different matter entirely...