I'm breaking the mould and saying I'm team counsellor because I think you need someone to guide you kindly but realistically through this. Someone who is going to support you but not let you off the hook because now is not the time to be taking the easy options. She's also not entirely wrong but that does not make it your fault
There is no point in feeling bad about yourself getting into it. Some of the best people do - I'd like to form a narcs survivor club on MN, we would be formidable!! This is going to be like a superpower when it's over!
But right now you are doing an amazing job and I think you sound like you have a lot of business acumen, and the determination and self belief (an absolute must) will make this and you a success.
As for the current situation and it's enormity? Don't think about it. Just don't. Think about the tasks within it, the various elements, think about maybe combining various elements to be more efficient. But do not think about its 'enormity'.
My god if anyone thought about enormities nothing would get done! I never do this the second I start I just go 'la, la, la not thinking about this, not going to go there' and distract myself. as a rule this isn't a skill I have but when it comes to the big stuff I know it's too important and so I do. You will too.
Your elements are currently
1 extracting yourself from him physically without getting screwed over
2 getting your business started
3 supporting yourself and the children while doing both
4 sorting out a settlement post extraction and getting the money.
And don't read the news or watch it. It is of no use to you. It is deeply depressing and of almost zero use to most businesses - certainly to mine it has been.
I think that your number 1 had got to be finding a way to separate yourself (with children etc) and this business, your precious baby, from him physically while not getting screwed over financially. All roads lead back to that - it was the same for me. Nothing was going to work until he was out.
So your most important team member right now is a very good Rottweiler like solicitor. Post a new thread here giving your vague area and ask for recs.
Though in these days of Covid you could even do Skype and get one from anywhere. With even an hour free. I know you have but find a really really good one. This is your team and you need the best. That to me is your number 1, must important task.