As your husband is a descendant of Portuguese citizens (his grandparents), he is eligible to apply for the Portuguese citizenship provided: his grandparents never lost/discarded their Portuguese citizenship; he can prove his links to the Portuguese community. Also, your husband will need to prove his descendance. This can be achieved by gathering his grandparents' and parents' birth certificates, as well as his own, and providing them to the authorities. Once the Portuguese citizenship is granted to your husband, you can also apply for it, provided you are married for more than three years. As for your U.S. citizenship, no harm will be done by it as Portugal allows for its citizens to have double citizenship.
