I know to know what happened? Could someone direct me?

You can find some information at following links:

http://scroll.in/article/774506/how-bajirao-and-mastani-became-a-byword-for-doomed-romance

http://qz.com/575194/historians-know-very-little-about-mastani-or-her-relationship-with-bajirao/

Exactly what my wife said. They should have written some text at the end of the movie

kashibai raises both her child raghunathrao as well as mastani's child shamsher bahadur. shamsher gets to rule banda and kalpi region in northern India like his father's wishes and is loyal to the maratha empire, fighting with them in the third battle of panipath and dying in the battle. on the other hand raghunathrao though initially conquers parts of north India for the maratha empire but after the third battle of panipath tries to conspire against the maratha empire enlisting nizam's help but is defeated. later he gets the peshwa narayanrao (his nephew) murdered and forcefully becomes the peshwa for a short time but is soon overthrown. he again unsuccessfully tries to enlist first british and the portuguesse help to become the peshwa but his attempts are unfruitful.