Sorry to hear this as it's so tough and nothing is really gonna help right now. I dread this too as my current pup is 13 yrs old.
I've posted them before but these are the two best tributes I've seen in a while.
SVP nailed it about the pain being the cost of the transaction and dogs being grace. I'm not a big country guy but that Chris Stapleton song is spot on too.
The part of his article that Peter King links to in that tweet really helped me a couple weeks after I lost 2 Boxers within a relatively short period of time years ago.
You wont find truer words than this:
[BGCOLOR=rgb(255, 255, 255)]"The easiest way to not feel this grief is to never have a dog. And what an empty life that would be."[/BGCOLOR]