Q: Library + divorce

See Backup your iTunes for Windows library with SyncToy. Make a clone of the library for one of you to take away. Once the libraries are separated you can each delete what you don't want to keep. With music DRM isn't an issue but with movies, tv shows and apps you'll either need to authorize the computer you use or abandon those items and start over. You cannot reassign purchases from one Apple ID to another. Hope you can manage it all as amicably as possible.

tt2