Hi op
I just found your thread and wanted to add another handhold 
I've only skimmed your posts (apologies everyone else) and I know it's only been a few days but how are you feeling? Did you get to speak to your GP?
I know you're in free fall right now. And I don't want to trivialise your feelings. But it WILL get better.
You have your wonderful children. And you always have us here. You are not alone.
Don't focus on the years/months to come. Take each day. And try to find something for you, just you, each day. Sitting down and savouring a cup of tea, five minutes of yoga, a hot bath. Whatever you can/want to do.
All the feelings you have right now I can guarantee there are women here who have been there. You're not a million miles away from me last year.
But I know it's hard to see things from my point of view when you're right in the middle of it. Speak to your gp. I think some help sleeping will work wonders. They might have local groups/counselling/contacts etc for real life support
Take care of yourself. You will get through this 