Conversion back to hindu invalidate marriage done under muslim law

marriage cannot happen over affidavit, if you have to the same, you have to approach the court of law citing justiciable reasons for the same and by an order of court the same can be done and by no other way it can be done.

Well, conversion of religion is your fundamental right guaranteed by our constitution. However subsistence of marriage after conversion is a matter of controversy and depends on various circumstances. The law stands differentiated for a Muslim woman and a muslim man as per the relevant provisions under the Dissolution of Muslim Marriages Act, 1939.
It is better to consult with a lawyer who practices family and personal law, in this regard.