If you're going for full custody then don't worry about husband's flakiness. Document EVERYTHING (i.e. dates, things taken from the house, accounts changed, money charged during separation, etc... ). You do need to build up a case in the event this all goes through.
As I've already told you, expect him to be VERY mean and to do terrible things to you. That's typical for MLCers in divorce. My husband did it. I know you are angry and hurt and want to lash out at him, but he will not make this any easier for you if you do. If you can stay calm and try to be amicable there is a chance he will calm down over time and lose some of that anger. If you fight him on this you won't make things any easier for yourself and your girls.
One more thing, keep in mind that the divorce lawyers will want this divorce to go through and usually add their imput and make the situation even worse. I observed this during my own divorce and have seen it in others. Often they do encourage their clients to ask for more than they are entitled to, build distrust of the other party and will tell you things to get that anger to the boiling point.
So... try to stay calm and rational. Don't let the ugliness drag you down to that level.
There is no arriving, ever. It is all a continual becoming.
