Hey @eventermom
Sorry to hear that the updated caused an issue.
If you received a critical error you might have received an email that will allow you to log in to your site with troubleshooting mode. If you can do that, then deactivate The Events Calendar and our other updated plugins.
If you didn’t receive an email and cannot log in, then what you can do is log in to your server via FTP or to your file system via the management console your host provides, go to the folder of your site, navigate to “wp-content/plugins” and rename or delete “the-events-calendar” folder, or the folder of the plugin you think is causing the issue.
After this you should be able to log back in to your site and install an older version. More info on that in a few mins.
Andras