What a coincidence. My 15.5 yo Shepherd mix is having surgery to remove a softball sized tumor in her abdomen Wednesday. I came home at lunch to find it had hemorrhaged. Vet says she's otherwise fine and if she survives surgery she could live a yr or two. I thought she could manage to get by without surgery since it's benign but now that it's bleeding out it's not an option. So I can certainly appreciate your emotions right now and hope it goes well.
You can see part of tumor here in this picture.
Oh my! Prayers offered up for your beautiful dog too. In a way, I wish this object was a tumor. But its something she decided to eat. Silly girl. Let me know how the surgery goes. I will say a prayer for her and you.