I know the feeling. I've had two dog deaths, one went out of nature, the other we had to put down. The first one was this adorable and just big pupper from a shelter named Sydney. The shelter said she was 7 or 8, but the vet said she was really pushing 12. She was old and tired out easily, but she was very loving. We feel she was abused in her earlier life because she would be very scared of the broom and other things with a stick. Any way at the very last days of her life she was super duper energetic, couldn't explain why. She was jumping all over the place, running, overall a complete 180 from the tired old dog we knew. Anyway one morning she went out for a walk, she was slow again, seemed so tired. She came back in and went to her favorite spot to lay down, our other dog Jetta, who was actually our first and much younger than her who was her best friend sat down next to her. Sydney then closed her eyes, and peacefully went to sleep and never woke up again. I think she knew her time was coming, and wanted to give us some fun memories at the end, but she didn't need to because we loved her and we were and still are so happy that while we had her only for the last 3 years of her life, she was loved and we hope she felt loved.

Jetta passed away later as well. Jetta was my first dog from when I was 9 years old. She was always super duper energetic and of course loving. She would bark at a leaf falling down, but she was just a big old chicken really. She of course eventually got old, but still tried her hardest to make us laugh. Eventually she got so old that her walks were quicker because she just wanted to go home and lay down. After being alive for 10 years, she started to have something grow out of her leg. It was this big round thing, and it got worse over time. We took her to the vet and the vet said it looked like cancer. He gave her about a week, and she ended up living for another year. You'd never know if it was hurting her because she never showed it. Any way one day it burst and puss and blood went everywhere. We bandaged her up, but she could no longer walk. It became apparent that she could no longer walk, this was her end. My mom and sister couldn't bare to take her to the vet, so my dad and I did. Jetta had the greatest smile in the world and could cheer you the hell up by being in her presence. Even though she was in pain, even though she had a feeling there was something wrong. When you said her name, she was smiling so big with her tongue out. The vet came in and gave her the shot, she didn't wimper, she was so tired. She put her head down and my dad and I were with her the whole time, then her breathing slowed down until it stopped. It was so hard because we had to put her down and make the choice and to this day I still remember it.

I miss both those dogs and I can tell you losing and animal is the hardest thing in this whole world. I wish you the absolute best in this OP, and just remember something. They may be gone, but the impact they left is still there. And always remember she loved you and you loved her, and at the end that was the best thing you can do.