Re-marriage without obtaining Divorce or Nullity decree means, the female who is willing to do that with knowledge of facts of either side for the re-marriage, will not get the status of "wife" in the said re-marriage, but just of "concubine", consequently there will be a lot of difficulties for maintenance, succession etc. It is told that, immediately after the first one week of marriage, there will be sufficient grounds for divorce, thus why to do re-marriage without any legal protection.
About proof of present spouse's re-marriage etc, there is no need of direct evidence or photos. Circumstantial evidence is sufficient. U/s 134 of evidence Act, the Judges have the power to presume about the Evidence produced by the parties. Thus please file the litigation to get "relieving order" from the present marriage. If the female will not file Application for Maintenance, the Divorce/ Nullity proceedings will commence immediately and if the Judge is a good man, within 6 months, on contest, you can get Nullity or Divorce decree, thereafter start new married life.
Wish you all the best.
12 pm of 29-10-12