I'm guessing it was your dd's..
Remember that they are still kids and for them to think about mommy being in pain all the time and not to mention if you weren't around at all, is very scary.
Some adults never learn to cope with family members that have long term illnesses or chronic conditions.
You were the supermom that took care of them and made lots of money- they had a feeling of security then.
All that has changed, and too maybe they were hoping the surgery would "fix" things more than it did...

This just popped into my head,
Have you looked for any books to give them on coping/dealing with the illness of a loved one?
Role changes , coping skills, that sort of thing..