Many couples are surprised to find that once all the costs are counted, you are not much better off financially if both parents return to work. This may or may not be true in your case. The only way to know is to sit down and make a list of all work-related expenses and do the calculations.
A simple process that will give you a rough estimate is as follows:
Subtract total costs from the total NET income. The amount left over is the actual amount you will have from the second income.
Once you know how much (or little) your second income adds to your household budget, you may be able to find ways to cut expenses. Read books, blogs, and talk with other parents to get ideas. It may be possible to cut expenses enough so that one parent can stay home.