You have no reason to be guilty. As a doctor, I know from your stories you did much more than many families would have done. This type of survivor's "guilt" is normal, and there is the sudden withdrawal of the stress associated with her care from your life. It is a form of grief and may take months and even years to dissipate. The best antidote is to know you did the best you could at the time and to take care of yourself now.