Barbiecat, I am so sorry to hear that your handsome Meezer Koko has gone to the Rainbow Bridge after 18 wonderful years with you.
I know how much it hurts to have to say goodbye to a heart cat after having them be a part of your life for so long.
I had to say goodbye to my cat Samantha after 20 years with her, I didn't start to feel better until I added my Meezers Milly & Izzy to my family to fill the empty space she left when she was gone.
Sending hugs your way.