I have been there too! A couple times as well. And it is hard. But with our 18 year old kitty I decided enough was enough and I did not want her to decline to the point where she was not her anymore. So when the vet said she was in the stages of liver failure I decided it was the right time. She had had a wonderful life. She was dh and mine's first as well and our sweetest. It was a hard one for sure. But I did not want to be away and have her get worse. I like the idea westtexas gave about leaving her at the vet's while you are away.
Is this the first time you have had to make this call?
All I can say is go with your heart. And remember do it for her not so much for you. Sometimes people will keep their fur friends around longer then they really should. More for them and not the fur baby. Does that make any sense?
Our's actually told us it was time. Sounds strange but she did. I had had another cat that we let it go to long and she passed when we were not home and my heart still hurts over that one and I really did know deep down that I should have done it. But she was in heart failure so kinda different. But she was my first and that is hard if you have never delt with it before.
Good luck and know we are all backing you up no matter what you decide.