How to fix my corrupted APFS container?
Your GPT Structure looks ok but just to be sure, there are a few things you can do. However, before proceeding, back up all of your data (time machine works well). Then proceed to 


Download Gdisk for mac
Install the package
Open up your terminal application
enter the command sudo gdisk /dev/disk0
Enter your administrator password
A message will appear. If something is broken it should auto-repair itself and look something like this 


  GPT fdisk (gdisk) version 1.0.3 

Warning: Devices opened with shared
lock will not have their partition table automatically reloaded! The
protective MBR's 0xEE partition is oversized! Auto-repairing.


Press x, hit enter
Press p, hit enter
Press o, hit enter
Press q
Copy and paste the results in your answer.
Close terminal
Go to the App store
Download Mac OS High Sierra 
Get a USB stick
Go to https://support.apple.com/en-us/HT201372 and follow the instructions on the site.
Restart your mac with your newly created bootable USB of High Sierra (or corresponding OS)plugged in, while holding down the 'Alt' key.
A boot screen will appear.
Select the option "Install Mac OS High Sierra"
Once in your installation screen, go to the "Utilities" menu and select "Disk Utility"
Click on your hard drive and hit the "First Aid" button. Then use the first aid button/tool on each of it's partitions/containters.
Exit Disk Utility. Reboot. Check if things are fixed. If not, continue with instructions....
Reboot with USB inserted again, and go back to "Install Mac OS High Sierra".
Once in the install screen, click the "Install Mac OS"
!IMPORTANT! - DO NOT FORMAT THE HARD DRIVE OR ITS PARTITIONS.
At the "Select the disk in which to install" screen, select your disk, but DO NOT FORMAT. Then hit the "Install" button.
Wait for the installer to finish.
Reboot.
Check and see if things are working. They should be. Done.