Oh, 9Lives!
Reading this brings tears to my eyes. I had a cat named Morris who was 20 years old and went through all of life's ups and downs with me. He was my "support" in bad times (I'm single) and a real comfort to me. I knew eventually I would either find him dead or have to make the excruciating decision to put him to sleep. It was the latter. That was the end of September and I still cry when I think of him.
4 years ago I brought another cat into the home, Kali, so when Morris died I would still have a furbaby in my home. Like you...I was checking to make sure where she was one day before I left home and found her curled up on the couch...dead at 7 years old. I saw her that morning and she was fine...no signs of illness prior either.
So, I truly do feel that pain with you that is so very raw right now.
Two recommendations that might be helpful for you:
1.
www.rainbowbridge.com - a WONDERFUL animal grief site that has a chat room. Everyone there loves animals and moderators are there to make you feel welcome. You don't even have to chat...just listen. I think I sat on that site for weeks after I lost Morris.
2.
www.thecatsite.com - As the name implies, this is all about cats. VERY informative and friendly site. It has a grief section called "Crossing the Bridge."
PLEASE feel free to email me (email in my profile) or PM me. This is so very close to my heart and I do understand how you're hurting.