it seems you might still be grieving which might take up to about 2years post the incident, however you might find reading about CBT cognitive behaviour therapy and other psychotherapy literature helpful. there is also a lot of self help online. you should not blame yourself for whatever might have happened, thats the life cycle we are all going to die one day or another. the important thing though is to understand that we cannot do anything to prevent death when its meant to be.
hope this helps
The psych nurse