Chris, I whitnessed this first hand in our family. Grandma was having trouble managing her diabetes so mom moved in with her parents to help out. Things got worse with grandma and the focus stayed on her. Looking back this was when things started to change with grandpa but we didn't notice it. When she finally passed away it became obvious something was wrong. Things continued to go down hill with him, but we made the commitment to keep him home as long as we could. This went on for two more years but by last spring we knew we couldn't keep it up. Besides mom being there 24/7, I'd spend most of my days off maintaining the property, and dad ran errands most everyday. Needless to say it took a huge toll on us all. By the end of spring, his mind was failing bad. He had lost most of his short term memory-he didn't even know when the seasons changed. Around this point he would get agitated quite easily and it took less and less to set him off. He didn't get violent, but he would go as far as grabbing mom by the arm. Eventually the doctors had to up his meds to the point to keep things under control, he was pretty much asleep. It was tough to do, but the consequences were so much worse. We finally put him in a nursing home in the fall, but true to his word, he didn't last long. A week latter he passed away. A few months later mom became ill and was diagonosed with stage 4 pancreatic cancer. Once again the warning signs had been there for months, but we had been so focused on taking care of him, that things were overlooked. Whether or not the doctors could have done anything had it been caught eariler we will never know-she passed away April 6. While she was battling cancer, I became her care taker and was wiped out after three months. How she did what she did for 4 years, I have no clue. The point I'm trying to make is you need to make your well being just as important if not more than your dads. If something happens to you, what would the rest of your family do without you? Decisions like this are tough, but you have to keep your wellbeing in mind too. All that anyone can expect is for you to do the best you can. I highly doubt your dad would fault you for your decision if he were able to comprehend the situation. I know when mom got bad, she knew how hard it was for us and was willing to go to a nursing home if it came to it, but thankfully it never came to that.
Hang in there. It's tough but you'll get through this.