Many couples are surprised to find that once all the costs are counted, they 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 will show what that second income costs you. The amount left over is the actual amount the second income will contribute to the household.
Once you know how much (or little) your second income is contributing to the household, you may be able to find ways to cut expenses. Read books and research the Internet for information. It may be possible to cut expenses enough so that one parent can stay home.