I was on the other side of the world when my father was declining in health... fortunately (ha...) it was physical and not mental.... however, when I arrived for the last week, it was starting to be mental as well. It was a strange time, but I can only imagine that it is much more difficult for you as it is spread over such a long time. 

Stay strong, and remember that this is the debt that we repay to our elders for the times that they looked after us when we were young. It is our duty.. and a good one at that.