Our old cat made his last trip 3 weeks ago. I was away so i couldn’t be there so my wife had to do it alone, including dealing with the girls who were very upset. It was the right thing to do though, and sounds like it will be for you too.
Depends how old your children are, but i wrote a letter from Fat Jasper (who wasn’t fat any more once his insides had given up working properly) to the girls. Sounds morbid but i think it helped. ‘He’ told them that he missed them and felt sad that he couldn’t see them any more, but he’d always remember them and the nice times they’d had. He told them that it was kind of them to let him go when he needed to, and that the vet had been very gentle and he didn’t feel anything when he left our world. My daughter has it in her school bag now, so when she misses him she can read it and she knows he is in a happy place, where you can have chicken every day and sleep on the beds. And there’s no dogs allowed!
I don’t believe in heaven myself, let alone a specific cat one with no dogs, but at times like this if it helps my girls get through, it’s OK in my book.
Be strong; at this time it’s the last kindness you can give to an old friend.