All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Your marriage to that man does not become invalidated just because he got married to that Hindu woman. It should be mentioned that it is not permissible for him to marry her since it is forbidden in Islam for a Muslim man to marry a non-Muslim woman who is not from the people of the Book. For more benefit, please refer to Fatwa 87895.
However, if he apostates and goes out of the fold of Islam, then your marriage to him becomes void. In which case, you are obliged to separate from him and not allow him to have sexual intercourse with you. If he re-embraces Islam while you are still in your waiting period, you are still considered his wife without a need for a new marriage contract.
Allaah Knows best.