I am so sorry you have to go thru this. It is heart wrenching. When we had our dane put to sleep for bone cancer it was devastating. I still cry when I think about it, now i wish I had done it sooner, all of the treatments we put him thru trying to save him.I now realize we were being selfish, but it is hard to let go of someone you love. I know in my heart it was for the best and in your jacks case it is the same. This way she is out of pain and any torture she might be going thru. She has a better place in dog heaven where she will once again be a happy healthy dog waiting for you and her babies. The main thing is to not feel guilty you have done everything you can for her, and I am sure she loves you as much as you love her. As humans we can only try to do what is best for our animals that we love so much.