I married with a girl in Dec-1998, But the fact came to my knowledge , that she was married and Her marrige was registered as per Hindu Marrige act with registrar on 2nd of August ,1997 with other person. And I came to know that she has kept relations with that person during the course of our marrige life. She has admitted now about her previous marrige & further admitted that They have taken divorce on 16th August,1997 with mutual consent on stamp paper which is notarised. My question is (a) Is the divorce taken on stamp paper in presence of notary is valid? (b) can our marrige be null and void on that ground.?