What is life??? Life is all nothing but a mere stage set by the Almighty, where you act according to his wish... Where he decides when you will come to this world and when you will leave it. I agree we develop relationship and love with the people around... And when they leave this world it not only hurt us but also tears us from within... But at the end of the day thats life... Happiness and sorrow go hand in hand.
One has to be strong, your being upset will not bring them back.. Rather it will disturb their soul.. They will never want to see u upset.