Q: How do I save all my photos with shared apple ID when we divorce?

Import them to your Mac or PC:

PHOTO IMPORT IOS TO MAC/PC

You should always do this anyway on a regular basis.

Alternatively, you can save them to the new iCloud Photo Library, but be aware that it is a Beta version at present:

iCloud Photo Library beta FAQ - Apple Support

Cheers,

GB

Assuming the photos are stored in iCloud, click "Photos and Videos" here:

Archive or make copies of your iCloud data - Apple Support

Or you can download Skydrive from Microsoft  fr the App store - for free and sync your pictures to the Photo Library that only you can sign in to - you will have to create a Microsoft account or Outlook.com account