Walt, its hard to hear of this news, and what you are facing, but you may find solace with your friends here, suggestions, advice and care, to help you bolster up to do what you must however you do it. Sorry to hear of this and the grief that may accompany it.
I felt the same about the farmer I helped for years, it was very difficult, I had see him suffer many times leading up to the end, and had to come to grips with it somehow, knew him since day one here on this earth, you think back to all the memories, the times, etc. He fought off the health issues for years. I sat with him one last time for about 3 hours, usually the same conversation and current affairs, but he was fading, needed assistance, and I knew then with this internal bleeding problem, he won't be here much longer, 2 months later he passed away and I paid my respects, I remembered him as he was and though I wanted to see him again, I was ok that I did not, knowing the last time I visited with him, I had to accept the situation, there was no other choice, now or later. It was not easy when he passed, I felt a ton of grief from it, but as days passed, it too faded, I have fond memories, lots of photos and the pride knowing that I worked with one of the last farmers in the area of the town where I grew up, worked with him, his sons and enjoyed every minute of it, so the good does balance the not so good, or so I like to think. You may find solace in this experience, and maybe not, but I share it only to help, it certainly was not easy, but I focused on the fun memories over all the years, and that was well over 40.
You do as your heart tells you, no shame in it, take breaks as you need them, you are human and its what gives you strength. Take care and be well, truly sorry for the difficult times you may face ahead.