Pat,  There is nothing that will prepare you for your sisters death.  If there was there wouldn't be someday of us on this website trying to figure out how it is that we could be in such pain and don't know what to do to cope.   I am going to say that reading here will let you know that you do not suffer alone.  Each of us is impacted by a certain relationship that meant the world to us.  Mine was my husband.  I started studying physics right away and have used that as one of my tools.  It reminds me that the cosmos is a lot larger and there must be something outside of this small focus we normally reside in.  I wish as much peace as you can find in this difficult time.  We are all here for each other.