Hi, Angela,
My second husband died of unknown heart issues in our bed in his sleep as well. I wasn't home. What if I was??
Honestly, I quite likely would have woken to find him dead next to me as you did. Sometimes, there just isn't anything we could have done to have made a difference. I know too many widowed folks - men and women - who were there and did the whole CPR routine and couldn't save their spouses, either.
Right now, think about taking care of yourself. I know that your kids lost their dad and his family lost their son and brother, but you aren't responsible for them right now. Remember that everything that was his is now yours and you can take all the time you need to go through your home and his stuff and make decisions about how to distribute or dispose of anything. DO NOT let anyone pressure you into anything. Very little needs to be done NOW. Things can wait...and you will begin to realize how long it takes to get things done and how you can get spurts of energy to do things and then spend periods of time paralyzed and unable to do anything. This is all normal.
Nightmares...tend to fade over time. You might relive those moments over and over in full technicolor, but my experience is that even the worst of those fade over time.
Hugs,
Maureen