I'm confident you let Ghost cat fulfill her purpose, the reason God put here on this Earth, in all the good things she brought to your family. It's praiseworthy that you had her companionship for so long and were able to let her go with a painless passing from the needle at the vet's.
What a great long life she had thanks to you and your family...and how blessed you guys are to have had her in your life too. These sad times will pass and only happy memories will remain. So sorry for your loss and sadness but thanks for sharing your story.
I know it was a hard thing to do, but you did the right thing for your beloved pet. We lost our pet 2 years ago (he's my avatar), so I know it feels like losing a member of the family. I feel for you brother.