It appears you've been targeted for a new type of phishing attack using Google Calendar instead of traditional email.
The event probably shows up on your calendar something like this:
Don't be alarmed if this shows up. This attack leverages a default setting that automatically adds invitates to your Google Calendar in an attempt to show up more frequently in your phone, reminders, etc. There are two steps we are recommending to clean up your calendar and ensure it doesn't happen again.
1. From your Google Calendar, click on the "rogue" event and hit the trash icon. In the pop-up for that event, select All Events. This step removes the existing rogue event and all recurring events from your calendar.
2. To ensure that future invitations don't show up on your calendar automatically, we recommend changing your default event settings. ***Please note that by doing this, you MUST respond to an invitation in order to see it on your calendar.*** Using this link (https://calendar.google.com/calendar/u/0/r/settings ), find Event Settings in the left menu. Change Add Invitations to my calendar from From everyone to "When I respond to the invitation in email"
As always, please feel free to reach out with any additional questions.