Michael, I'm sorry you lost your father in this manner. I do have some understanding of what you went through, as I lost my mother from breast cancer. Returned 12 years after she had her second mastomeny (sp). She spent the last two months of her life in the hospital almost completely paralized. She could only move one leg. She could talk and swallow, but couldn't chew. Her funeral was at 10:00 am, Christmas Eve.
Not long ago lost my sister-in-law to ovarian cancer. I will have a DNR for myself. Doctors put her on life support for a week before finally letting her go. When she went into the hospital with pneumonia she knew she wouldn't be coming home. I can't describe what it was like to watch that machine breathe for her as her kidney's shut down.
Even after going through that, I still believe that when God created those two lives, they were His alone to take. There's no way for us to know His purposes for those lives or ours, even in the end. IMO, there's no way to separate their pain from our own in these circumstances. To know, with absolute certainty that ending their lives prematurely isn't also being done to end our pain, as well.
Thinking back to those days, this Resurrection Sunday morning. Remembering a blessing. A year after I lost my Mom, God called my Dad home swiftly. His life ended in just a few moments, at most, when he had a massive heart attack.