In life, there are going to be unforeseen "tragedies" that will leave us reeling as we try and process the "why's" and the "how"s" as we try and make sense of it all.  It may feel like we can't go on -- some may not even want to go on.  My advice to you is to hang in there and allow yourself to feel every emotion that you need to, so that healing can begin.  The "tragedy" will always be etched in our memories, but one day we will get to the other side of it.  We will be able to "breathe" again, and not feel like the life has been sucked out of us.  We can't give up because we will get through this.