That is the law and it is harsh in situations like this. That is why it makes sense to change the law to allow people to apply for a legal status (short of citizenship) , with a period like 10 years after which they can then  apply for a permanent status that could allow them to reach citizen status. We forget how badly we need immigrants-- look at the farmers in Iowa and other points in the Midwest seeking changes in the law to let them continue to employee immigrants. An even larger problem is that without immigrants we will end up like Japan and much of Western Europe. Our birth rate has been declining for 10 years and soon our population will unavoidably shrink and will become older like Japan with stagnant economic growth. What keeps us from ending up like that is our growth in immigration and the higher fertility and birth rates of immigrants.