Can a RTI be filed to get marriage details of someone elses marriage

Dear Lawyers, While contesting my DV case, I come to know that my wife cheated me & had been married to a guy few years before our marriage. But problem is that wife married to that guy in Arya Samaj Temple and when that guy left her few months after their marriage, she married me, without divorcing him. But wife family remains quiet on that issue and supporting her in her cheating. They want me to pay huge maintenance for filing mutual divorce. To prove my innocence & book wife & her family behind bars, I want to get copy of marriage certificate/marriage register from Arya Samaj Temple. As till now I dont know the exact marriage date and the name of the guy whom she married, I want to file RTI for whole year to get marriages detail. Please help me how I can get marriage details legally from Arya Samaj Temple. Also what are other mean to fight cheating case if I dont get previous marriage details from Arya Samaj Temple.