Bottom - 2 years ago, my DH started our business. I backed him. It was something he had always talked about doing and external events meant the time was right. I told him to do it now, whilst I was in my early 40's and the children were still young enough to be 'portable' - so if it all went wrong, we could sell up, down-size and start again. I told him, if it was 10 years from now, I would say "No, absolutely not!".
I told him this was his chance to "live HIS dream".
He asked me for 18 months support - doing the accounts and admin. I agreed, providing it was 18 months and no more (within reason!).
So, 2 years down the line and I too am STILL doing accounts and admin and a whole load of other stuff I have NO IDEA about. I am a sales person through and through. i DO NOT do accounts/admin/other stuff I am currently doing. The thing is, I cannot just say "that's it, get a real person in to do this" because the timing isn't right. So, I have to carry on. Then he gets arsey with me because this, that and the other hasn't been done. I say "Remember Mister - THIS IS YOUR DREAM. NOT MINE!"
The reason I tell you all of this? Because it sounds like you and I are living the same life. We too have two children (aged 8 and 6).
I haven't got any other top tips but I hope that just the knowledge that somebody else is out there, going through nearly the exact same shit as you are, helps!