Marriage on mutual agreed basis of widower with divorcee

I don't intend to spoil your party, but if I were you, my antennae would be on alert mode. In this day and age, case status can be found even by Party Names in many eCourts website, case number notwithstanding. Even otherwise, if the lady is aware of the fact of ex-parte divorce, she can be presumed to be reasonably aware of at least the Court which dissolved the marriage and the date of decree of divorce. Even if  a single date is known, the rest may easily be traced from the Court causelists because in my experience, most District Court staff retain old causelists with them up to 1 to 2 years, noting the next date of hearing on the margins for each case. I'd suggest you follow it up seriously with some Advocate's Clerk to verify the facts. 

Agree with Adv Atul.

First to obtain certified copy of divorce decree then proceed further.

Agreed with above suggestions.