I heard the "keep the big gun cocked" from my cousin who has seen many such broken marital cases in the construction business. He told me that it was necessary to "Strike fast and strike hard". My lawyer said not so - "lets work in a more friendly business manner, but with the upper hand of striking first".
And you do need to start high in your demands.
But, there is a thing to consider. If your H sees that he is going to be hurt majorly on his long term future finances, he may pretend to want to come back so that you back off the big gun. You need to not be so easy to take him back.