My thoughts go out to you for this event in your life. I send my hugs to you in this hard time knowing, as you know, that it was a good way for her to pass, so while it's hard on you it was not a bad thing.
So sorry for the loss. They may be just animal but so much more, like furry kids. She had a wonderful life with you. I have had to deliver several family pets to be put down. Not easy for sure. Only Sweet Sabrina (My adorable old Calico cat, 19 years old.) Passed at home. She will be with you always. Do you have any of her offspring?
I am sorry for your loss and I know exactly what you mean about the being happy part. I made several mistakes over the years prolonging the decision to put a pet to sleep and I have the memories and regrets of it and then the ones that I did take and it makes it so hard.
Rabbits I think we all made the mistake of waiting to long. Tina's mother Lola was my first Cavalier. I saw her at a dog show it was love at 1st sight. At 14 Lola's back legs became very weak, I pumped her full of inflammatory drugs, she would eat well wage her tail but often fall down and struggle to get back on her feet. 2x after watching her I made appointment at my vet. Both times right before appointment I would call and say I wasn't coming. One day I came home in find lola in a puddle of her urine, the urine was cold so I knew she laid in it for hours. That is when I realize I was keeping her alive for me.