First of all her marriage with you is not valid, it is void ab-initio for the reasons that:
She being a foreign national, she cannot get married to you under Hindu marriage act, hence the solemnisation of marriage under the provisions of Hindu marriage act is null and void.
Her marriage with you should hav been solemnised under the provisions of special marriage act only, for that she should be a spinster or single or divorcee or a widow.
If her earlier marriage subsisted and the spouse was living at the time of contracting marriage with you then this marriage is null and void.
Therefore you can file a petition seeking the marriage as null and void by mentioning that you came to know about this only very recently.
After getting this nullity case disposed in your favor, you may remarry another person.