Hug, I've been where you are. The dark thoughts and emptiness. I've contemplated ending it as everything was just too dark, recently enough that I am still pulling my self out of that despairing mindframe.
It doesn't last, your life might not change significantly but your mental state will and you'll climb back out of this hole.
Who would protect and guide your children without you? Your husband, you've posted about him before and he doesn't sound like he'd give them the support they'd need, if he can't grasp keeping a computer safe from a sn child how will he keep that child safe from the world? Your mother, who allowed you to be abused and won't support you now... How will she raise two sn kids?
You are their only advocate, their only defense against the world. Their defender from those who don't understand.
If you won't stay alive for yourself, then do it for them 
We're all here for you, and your friend will be too soon... He's struggling too and may just not be able to cope with supporting you right now. That doesn't mean he doesn't love you, just give him time and let him know you'll be there when he needs you just like he has been for you.
Decide what to do about your marriage once you're clear of this low, decisions made when your mental health is so bad are dangerous. Just survive for now, then change things for the better.