There is software that can be installed that records keystrokes or monitors your activity. Do you want to catch her? Or just want her to stop ?
And how far are you willing to reset to keep her from tracking you?
Because car tracking devices and many other trackers are easy to get: spy cameras etc. it might not just be your phone.
Get a new phone and phone number. When you get your new phone don’t let the store synch to your new one. Tell them thanks but you’ll do it manually.
(Don’t save anything to the cloud turn off any cloud options and all sharing.)
Turn off any desktops, laptops and any connected devices.
Go all in - turn off everything at your electrical box.
Restart your electricity.
Reboot routers and modems. Then restart your devices. Keep your devices off when not in use.
Check your car for trackers. Check your house for spy cams. Check your wallet or personal items for air tags.
Don’t add her in to your new phone as a contact. It might be as simple as her using ‘find my’ to see where you are.
If she has to have your phone number for visitation or support etc, get a free phone number that will forward to yours, and give her the free phone number only.
If it still seems she has the ability to monitor, back up your devices (laptop, tablets, pcs) and factory reset them.
Cancel any joint accounts/ apps that are still hanging around or you forgot about. and get your own. (Password protectors, delivery apps, shopping apps, streaming services.)
Ditch the ring camera. Or if you must have it for security, get into the app and make sure you are not sharing anything. (Neighborhood notifications, with other emails etc).
Check your other major apps to turn off any sharing that you might have set up to her email or phone. It could be something as simple as Amazon prime and they snap a photo of your front door to show your package delivered and she’s on your prime too and gets that photo. Or your neighbors ring cam faces your door and you’re sharing neighborhood notifications. .
Treat Electronic and data awareness as important as situational awareness.