This is very true. When I lost my Mom to suicide 6 years ago I honestly expected everyone to blame ME. I was shocked when people expressed sympathy. I read a lot of grief books that said this was a normal reaction, but an inaccurate one and that we shouldn't blame ourselves. Yet my guilt was so strong that when I started seeing a therapist my first words to him were "I know most of your patients feel guilty and you tell them that they aren't supposed to feel that way, but I'm the exception to the rule. I am guilty." It took a couple years to accept that there was nothing I could have done to change things, but guilt still creeps in from time to time. Maybe - just maybe - the Anthony's feel some similar type of guilt for letting Casey do as she pleased all these years. Our situations are completely different, so I can't say that with certainty of course, but it does make a little bit of sense to me.
Parents usually do feel responsible for their children, no matter what their age is... and even if they try to rationalise they are not at fault. And then, there are those children who had reverse roles in their relationships with their parents... where the children feel responsible for their parent/s well-being. I am sorry about your Mum, Wishingtree. *hug*