Head to the chapel to start a cutscene will Father James trying to convince you to leave town and start over and with Donovan stating his opinion about having another "Sal Marcano" to run the city. You'll have two options now: leave the city or drive to the plantation house in the bayou to meet up with your underbosses to decide the fate of the city.
After reaching the plantation house, there will be two choices given to you for the last time. Rule Alone or Rule Together. I won't spoil anything but if you have worked hard and planned enough to keep your underbosses alive at this point, there's no point of ruling alone in the end. Make your choice and the ending you'll see will depend on your selection.