I think Onyx made some really good points hun.

Squirreling away a bit of money here and there isn't going to give you financial security. It might give you the security of knowing that you can up and leave and get by for a week or two. But to put enough away for anymore than that, then you're going to have to be hiding significant amounts on a regular basis for a long time... If you are thinking that there is still hope for your marriage (which only you can answer) then this probably isn't the best idea. If you're looking to create a way out, well this is one way out.

But TBH, if you want out then I tend to think you might be better just withdrawing a chunk of money from the savings/mortgage/credit card/whatever and getting it over with. That way it's out in the open and he can't pin the ongoing deceit on you down the track. Also, the other thing to keep in mind in regard to super is that it is now considered a marital asset and as such you can claim part of his super as part of a divorce settlement.

HTH and good luck hun