@Etotheipiplus1equals0
There are so many things I want to say to him.
So say them. Talking to the stars in the middle of the night has helped me through personal loses. Even if you don't believe in a Higher Power or Afterlife or anything like that, there's something immensely calming and comforting about the stars when you're dealing with the death of a loved one. And of course they'd be a special connection to your husband as an individual as well.
Allow yourself to cry, maybe even go to the park or out into the countryside with a friend or relative when the children are in bed (with a sitter), and have a good loud hysterical screaming fit there - take a pillow to scream into if you're afraid people will hear, but get it out of your system.
Write a letter to your DH. You can leave it with him, or make it into a paper plane and throw it in a river, or burn it with a candle, or bury it in the garden, or just keep it somewhere safe in a box of special things. The children can do their own for him too. Don't leave anything you wanted to say unsaid, even if you're angry with him and need to put that out there, that's ok too. There's no right way to deal with grief, but please don't try and suppress your emotions and battle on being 'strong', because that's a short term solution, and you'll find reality hitting you hard at some random point later on. Better to accept the pain and run with it now if you can. Accept help from friends and relatives. Give them something to do, even if it's just picking up a carton of milk with their supermarket shop, or posting a letter for you - it'll show them that you do need them, and they can better be there for you emotionally in the long run if you are able to accept their physical help now.