Coffee Par Kurukshetra: Bengal gone, party also finished, what is the INSIDE STORY of TMC split?

The game is over in Bengal. The player wasn't Mamata Banerjee, but Ritabrata Banerjee. Mamata Banerjee's party has split. 60 MLAs were elected on Mamata Banerjee's name, but now they have chosen Ritabrata Banerjee as their leader.