unbearable thoughts

I hear story after story of mothers who have lost more than one child.   I fear that happening to me.  I go to bed every night fearful.   I am so scared, not only of losing another child, but of finding anyone else dead.  the thought of that terrifies me.  I don't know how to cope.  the fear is overwhelming. 

why did this have to happen to us?

I know I sound like a freaking broken record, but I just don't understand. 

why?