So sorry, it's always hard to lose a loved pet.  It never gets easy, either.  The hardest was my second cat, Birdie, as she was famous at the shelter for being a very standoffish cat, not wanting anyone to touch her.  She was a big snugglebunny after she got used to me.  Loved belly rubs, would play "catch" with a ball suspended from the ceiling fan, tossing it back to me after she'd catch it.  She developed breast cancer and there was no hope. 

It is hard to put down a long time companion. Partly a matter of guilt in my experience. One wonders "did I give her a sufficiently good life to compensate for the loss of freedon? Did I wait too long? Did I wait longer than I should have?"  So difficult.

There's a blank spot on the kitchen floor now where her food dishes were, one less litter box in service and her collar is in the garbage (which has to go: its giving me pain). The vet gave her a look over, said she'd lost another 2 lbs--which was radical for her size--and agreed that it was Time. Yeah, I beat myself up a little with Did I do the right thing? (Yes, I guess). Did I wait too long? Should I have waited a bit more? (That one's a No per the Vet). Vet said it was the right thing, even though it's the hard thing. I said it's never easy for me. He said it shouldn't ever be easy.

That's so sad.  I have three collars from former pets that we've kept in the doggy drawer.  It's nostalgic to see them now, but it was so painful for a long time afterwards. I hope you get to that point soon.