one of my friend married in July, 2018. after 3 months of marriage, her wife started torturing him physically and mentally, ultimately she filed a case of 498A and DV act against friend and his family. no family member live with them ever. now my friend got a proof that her wife was already married and not divorced her previous husband. she filed same set of allegations against her previous husband and his family. he has certified copy of a case in which she admitting that she want to withdraw all cases against her previous husband and his family and want to go back and live with them peacefully. actually she is professional to do marriage, file case and extort her husband. now friend want to go court to declare his marriage null and void. my query is, what are the procedure for that and how much time it'll take.