Aw, Logan!
I know what you are going through. I went through something similar when I had to make the decision to let Leroy go. He developed heart trouble. After two weeks of love and cuddles he got to where he couldn't breathe. I decided to let him go. I couldn't let him suffer any longer. My prayers are with you and your family and Murphy! Enjoy every second you can with her. She knows you love her.