I know nothing we say is going to fix what happened but I hope you at least feel a little better knowing you're not alone! I went through something similar with my Mimi. It was her first litter and also my first time breeding. She had all the medical attention and care that I could have possibly given her and EVERYTHING was perfect. She held the puppies all the way to her due date and a few days before something just seemed off.. Anyway long story short, she needed an emergency c-section to get the puppies out. They had been dead inside of her for a few days and were starting to decompose. It was not only extremely shocking to go into the vet expecting to leave with a litter of 4 puppies and a healthy mom, but incredibly sad. I was SO excited for these puppies; I was planning on keeping two of them and I not only lost the entire litter but almost killed my dog too by getting her pregnant. I was depressed for a long time and even thinking about it now I get teary eyed and get sad. I have 4 little angel boys looking waiting for me & their mommy when this life ends for us. Think of them as little angels waiting for you to meet again some day
Remember, all dogs go to heaven!
I hope I made you feel a little bit better..be grateful that they didn't suffer for a longer period of time and that you still have your other babies with you <3