Hello, slow triathlete.
Sorry to know you're having this problem with your MacBook.
If you can startup in safe mode you may be able to download, install and run Malwarebytes to try to get a handle on this nasty critter.
Use Safe mode to isolate issues with your Mac - Apple Support
To start up in safe mode:
- Start or restart your Mac, then immediately press and hold the Shift key. The Apple logo appears on your display. If you don't see the Apple logo, learn what to do.
- Release the Shift key when you see the login window. If your startup disk is encrypted with FileVault, you might be asked to log in twice: once to unlock the startup disk, and again to log in to the Finder.
To leave safe mode, restart your Mac without pressing any keys during startup.