“How do I stop my wife spending?”
You probably can’t. But this can indeed be a big problem in a marriage. If she can’t control her spending and thinks she might want help, she should try Debtors Anonymous. There are many meetings in New York; a directory is at http://www.danyc.org. There are many frum Jews who have found relief there. For more information and to find meetings outside of New York try http://www.debtorsanonymous.org.