I read your post and found it deeply disturbing...life often brings us pain after the happiest times of our lives. I also asked myself the same question in many different situations (why me? why us? what have we done to deserve this? ) in different painful situations that I wished never happened. After many years I could finally see that life is a cycle of joyful days and painful losses that can destroy us if we let them, and this is the most painful truth:we will eventually feel pain when we loose somebody dear, there is no other way, but we can manage to persist living and not to give up on our lives, because life is not only happiness, not at all.
There is also a new question I've learned to ask myself: Why not me? Why was I thinking that could be immune to suffering?
I´m no different from the others, we are all human beings, with our own problems and weaknesses, diseases, etc.

I think that one must above all, feel grateful for having the opportunity to be here, to have friends, to do something ... Being here above all is bliss from the beginning and that fact helped me to get myself together and keep going even when I thought I could not.