Although we wern't married we owned the house together and that probably made me stay longer than I should have.
I told him, then moved into the spare room. Then I used www.rightmove.co.uk to track down somewhere to rent. I had to go right up to my overdraft to be able to put down the deposit. Its very modest compared to where we lived together but the atmosphere is very relaxed and I love it.
We both went to the bank to get our joint accounts 'unjointed'. The house issue is still ongoing, mainly due to him being a pain and dragging his heels.
Luckily I work so money ongoing wasn't too much of a problem, though of course everything is more expensive when you buy for one instead of two.
I don't have any family nearby, so it wasn't an option for me, but have you thought that someone would put you up for a bit while you sort things out. Or could you ask him to move out as you have little ones? For me, I knew he would never get round to leaving and then I knew we'd still be living together years down the line, getting more and more frustrated!
It was very scary and I was really low for a few months. I have just got of that in the last few weeks and am enjoying my freedom. It can be done!
With being nervous of all the mundane things that need to be changed, just tackle each problem as a single one, because if you look at it all at once its seems insummountable.
I hope that helps a bit. Feel free to ask any more questions if you want.
x