Thanks for using health care magic. It is so sad to hear about your husband.
I have gone through your available history. What you are having is adjustment disorder
with depressed mood. Diazepam
is very good drug for sleep but it has its own potential hazards including addiction. There are some non-addictive sleeping pills available like zolpidem which has very low addictive properties. You can ask your doctor for that.
Meanwhile you can try some good sleeping measures like avoidance of caffeine, Yoga, meditation
or breathing exercise
to have a good sleep.
I hope you can cope the stress soon.