Thanks. To be honest, your reply is a little over my head – I have no idea how to update PHP (or even how to know what version mine is).
To help others: I went into my cPanel and deleted the plugin file from my wp content>plugins folder. After I did that, all access was restored. I guess now I don’t have the plugin, but it seems my site is still running the pixel. I’m just going to leave it for now. Thanks @alissit for the link to access the admin, I’ll save that for future use!
I started a new thread to report the same issue. Watching for an update! Site is DOWN.