1. If she was married before, then she can remarry only after availing the decree of divorce from the Court,
2. If she has not obtained the decree of divorce and has married you, then your marriage is illegal & void at law,
3. She is still the legally wedded wife of her husband, not you,
4. The problem is her husband can lodge a police complaint against you bringing the charge of adultery for which you can be sent behind the bars,
5. Lodge a police complaint against her alleging that she has cheated you by marrying you hiding the fact that she has not taken divorce from her husband.