R.W.
I'm so sorry S.! Having a lifelong companion like that is very hard when you have to do the things you need to do to take care of them. My grandfather raised and bred Beagles. He showed me that your love for your animals goes beyond just food and normal care. You must show your love by not letting your animal suffer. They don't need to be in anymore pain than should be. He taught me that after a dog has lived a very good life, it is time to help it pass on. He also talked about surgery and how sometimes surgery will only put them in more pain and prolong the agony they are suffering now. It sounds to me that since your little puppy has so many things going on, that her pain will not be alleviated by gall bladder surgery. I'm so sorry that you have to deal with this. It is so hard on us humans to have this happen to us. My grandfather's advice has helped me so many times when my pets have become ill. My grandfather passed away last year and was living with my aunt. He had alzheimer's and didn't even remember our names or who we were but close to his death, my aunt's cat became ill and she had to put the cat to sleep. She came home so upset and of course, my grandfather (her father) asked her what was wrong. She told him and during that moment he was her father again, because he couldn't remember anything about her but can remember his beagles and he told her the same advice I just gave you. It was amazing that during her time of needing comfort, God gave my grandfather lucidity to help her through that time.
I know this won't be an easy decision. You can always get the Yorkie a new playmate to help alleviate her and yours pain if you choose that route. I hope I helped you some. My grandfather helped me several times with that advice, I hope it helps you too.