Oh PD... I'm so sorry. I lost my first grandbaby to miscarraige and had to put my beloved dog to sleep within one year. I don't care if you're a man or woman. Anyone who isn't crying in your position has no heart or soul. I'm crying for you, with you, bud.
I know hard to watch what your dad is going through. But the hardest thing is having to make that choice to end your best friend's days - even if it is for the best, to end their suffering. I know, because I had to do it.