If the person dying is still of clear mind, maybe have talk with him?
I am assuming that he wants you to be happy too and would respect whatever decision you make. There might be a chance that he would even encourage you to go on your trip as planned as long as you are happy.
Maybe he doesn't want himself to be a burden of yours and may even feel guilty on his deathbed if you don't go on your trip.
You will both have to be on mutual understanding that it the time you meet before going on the trip may be the last.
Note: Most tickets, even if non-refundable can be exchanged for a new ticket by paying a change fee. Perhaps you may be able to exchange the ticket for a new first class ticket starting at a later date (may have to pay fare difference) or even a ticket a a lower class such as business class (if new ticket is cheaper, the residual is forfeited).