As others have said, make sure you understand that moving up a tax bracket only means the income in that bracket is taxes at the higher rate, the other income is still taxed at the lower rate.
With $100k gross income you're at most just below the 22% bracket (meaning you're still in the 12% bracket). Things like health insurance, 401(k), deductible IRA contributions, etc will reduce that further.
You will certainly end up with more money if your wife continues to work unless her not working would reduce expenses (child care, eating out, household help, etc).