How do you know when to give up - on a sick kitty

I took Ms Kitty to the vet and had her put down. I hate myself for doing this. 17yrs and now she’s gone.
You made the best decision you could and did it with both mind and heart. As much as it hurts, it’s the best you could have done. Don’t beat yourself up over the decision.

The pain isn’t from choosing to end it, it’s from the absence of her in your life now.

Remember her in love and don’t let the rest cause undue pain...the end is always hard.