According to the release notes for 65beta, there is an EN-US version of the Provider for Google Calendar add-on available (see the Known Issues section).

I'm not aware of any way to integrate Office365 calendars with 65b. It is possible with TB 60, with e.g. TbSync.

How can I roll back out of the beta and into TB 60?

Uninstall the current TB (won't affect profile folder), then install TB 60.4 from https://www.thunderbird.net/

How do I make sure that my profile is saved and backed up? Where do I find it? It would not be good to have to start over :(

https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data?redirectlocale=en-US&redirectslug=profiles-tb#w_backing-up-a-profile

Thank you all is good now.