What a heart-breaking thing to have happened. My heart goes out to you at this sad time. It must feel like limbo to you, and your family. :'(
Can you make a memorial in your garden for Charlie with special plants, rocks, and an angel cat statue/figurine? Have a small service for him so that you can gather together and celebrate the life he had with you? At least it would be something to bring you together now to remember Charlie properly.
I wish you all a kind and gentle path to healing from your shocking loss.