Definitely lawyer up as PP have said. Can you use the time before the shit hits the fan to Miss Marple up all the documentation you can find re bank accts, pensions, savings, shares. etc etc? Do you know how much he earns? Is he employed or self employed?
You have two DC with him so the bare minimum he would have to give is 20% of his take home pay. As you are SAHM he may also have to pay spousal maintenance for you.
You can probably get a mesher order which would mean his name stays on mortgage but he would have to leave you and DC in home until youngest finishes full time education and then you sell home and split equity. This may not be 50/50% split as you can sometimes offset some of the equity in exchange for not making a pension sharing order on his pensions, so you might get a much higher percentage, depending on what other assets DH has.
Once you start divorce proceedings he is likely to turn nasty so he may even flounce off and leave anyway, but even if he doesn't, it is likely from what you have said that he will be forced to leave the house as part of the divorce settlement and an occupation order will be made in your favour.
He will make it sound like he holds all the cards cos he earns all the money, but, unless he is self employed and can hide a huge chunk of his money away, it is YOU who holds all the cards here.
Let us know how you get on and good luck.