Hi there!
Sorry for your experience.
Please keep a backup of your full site including the database.
The error should be resolved by uninstalling each and every instances of SP Page Builder from your site backend. Then download a fresh copy from our website and install through the extension of Joomla backend.
Sometimes admin module plugin can be overlooked when uninstalling or removing SPPB instancec. So please make sure you are removing all. After reinstall, please clear your Joomla and browser cache and check again.
The following forum link may help you as well:
https://www.joomshaper.com/forum/question/13409
Best Regards