Q: Access to my iCloud Photo Library by another user?

You would have to put the library on a separate volume where both could access it, or both users would have to log into the same apple id on separate computers in order to access it.

Let me correct that. For the iCloud Photo Library, the only way for 2 users to have full access is to log into it with the same Apple ID.

Use Photos and iCloud Photo Library on multiple Mac computers - Apple Support

If you give someone else access  to an iCloud Photo Library via your Apple ID and password they will also have access to your emails, messages, Apple Store account, etc.  Is that what you want to do? 

If you want to share all of you photos with someone else use a 3rd party online storage like Flickr or Shutterfly.