There really is not question which one of those this is.
I can't say I understand how you feel. I have lost people close to me but not that close. When I lost my brother it was hard but with my wife I hope I am the lucky one who goes first. Some pain never goes away completely but you learn to function with it. We have never met but I get the impression that you have an inner strength that will get you through until it gets bearable again.