If you go, you have to keep in mind that she sees things from her husband's perspective and you will not be able to "persuade" her into seeing things your way. It just won't happen.
Remember, she may see the child support as her money that is being taken away.
If you can control yourself, she may end up giving you more info than you think. A little insight in to why all of the sudden he is willing to accept your previous offer.