My heart is broken

My little princess died last night.(this pix was taken about 1 month ago or less) She had been slowly decreasing her food intake. I noticed about a month ago. So I went and bought different kinds of dog food to see if she liked anything else, but she didnt seem too. Friday, she didn't eat and was acting lethargic and I gave her some diced up chicken which she ate. Saturday I was really worried, I opened a can of tuna and she did eat it all. I went to Walmart on Sunday bought several different kinds of food again. But back in my mind a little voice was telling me that I would have all this food left over cause she just wasn't going to make it. I of course ignored that voice. On Sunday she wouldnt eat and didn't drink much and she looked just plain tired. Monday, I said if she doesn't eat or drink, I am taking her to the vet. I get home from work and she didnt eat the tuna or anything else we left nor did she drink and was just laying in her crate and wouldnt come out. She also looked like her breathing was labored. I held her paw and she felt cold. So I wrapped her in a blanket and my husband drove me to the vet. We both knew this was the end and she wouldnt be coming home, but we kept saying maybe she has a cold or something.(but we knew in our heart). We see the vet and the vet was a lovely lady and so sweet. She said she is cyanotic and her lungs and heart are failing. She said what we knew, she needed to be put down. With tears running down our faces we shook our head in agreement. My husband left he couldnt be there when they gave her the shot. They left me alone with her while the nursing staff got the paperwork to be completed before they could give her the shot. Brandy was laying on the table on a big towel, they tried to make it really soft for her. Her head was resting on my left arm and my other hand was on her tummy just rubbing her. She was having so much trouble breathing, it broke my heart. She looked up at me, kind of raised her body to get a good look at me and she took her last breathe. I started sobbing of course, the gal walked in with the paperwork to sign and I said she is already gone. She looked shocked and turned and got the nurse who came in with a stethoscope and she listened and looked at me and she said she is gone. I just sobbed and held her and kissed her. I will miss her soo much. I had her for 15 years.