Morally and ethically she should have told you but there is no law which bound her for this. Definitely it effects the child support of the kids. You can contact Child Support Department for details.

 I doubt that it will have that much to do with the child support, but if you are paying any alimony, that would be affected for certain unless stipulated in the divorce decree. Ethically I believe you were entitled to know, but I do not know of any law to demand such a disclosure.