Been there entirely too often myself.  I know how 
very bad it feels.  Huge hugs.

If good thoughts help, you're surely getting a 
ton of them flung your way tonight.  My crotchedy 
old ladies send their best regards to the boys as 
well.  They say that if they can hang in there to 
age 17, Steve and Clive can too.  One of the 
dears earlier in my life, Tammy, lived to be 
twenty in spite of fighting congestive heart 
disease for a number of years.  

Cats are incredibly resilient folks.  Let's hope 
this is true for yours as well!