I'm so sorry you and Callie are going through this. It is the worst thing about loving cats - that this time comes eventually, inevitably.
I really feel for you because I've been there a few times and my heart still aches - no matter how long it has been.
May you find comfort in all the joy she has given you over the years you had together, and the knowledge that you have taken such good care of her. She will always be with you.
I am also so sorry to read this. I honestly had no idea it would be this soon or I wouldn't have made a couple of "jokes" about sub-qs in an earlier post. I feel terrible about that, but I was just trying to put you at ease about doing them yourself.
Right now, though, my heart is breaking for you and DH.
Please don't worry. We had decided long ago that we wouldn't do any heroic measures because of her age and we'd let her go quietly and with dignity. I had to work through all the possibilities and I seriously considered starting to do fluids at home, but it really wouldn't extend her life for very long and we didn't think her quality of life would be anything near to what it has been.
Thank you to everyone for being so understanding and supportive.