Does he have to tell his second wife that he is married

I married a foreign woman after she became Muslim in a shar‘i marriage in accordance with the laws of Allah and the Sunnah of His Messenger, and I concealed from her the fact that I was married before. Is my marriage legitimate or do I have to tell her that I am married and that she is the second wife? Please note that I concealed this matter from her because the country in which we live does not allow plural marriage.