My wife left me & 3 year old child.

We got married in July 2014, my wife was Hindu before marriage & at the time of marriage she accepted & converted to Islam, our marriage was in a traditional way as Nikah was performed by a Qazi. In August 2015 she gave birth to baby girl. Everything was going smooth till the time she join her first job in November 2017. In May 2018 we went on a vacation & after coming here she resume the office & after 3 days I found that she is having a affair with office colleague. When i confronted her she left the home leaving the 3 year old child. She went to her parents place to stay & when I inform her wrong doing to my father in law even he confronted her. So on this she left her father place to & started living in a share rented place arranged by this office colleague. In the initial first month ( 5 June to 5 July) she told me that she wants mutual understanding divorce through court or else she will file DV against me. On 5 July she said that going through court procedure will be a long process so instead as our marriage took place in a sharia way we will end it through sharia way. In the initial days when she left the house she use to take updates of the child & talk to her. Later she decrease the communication with the child. Now she says that she wants the custody of the child. As a single parent I had dedicated my 100% towards my child, I can't even think of giving her access because of her adultery. Please assist me how I can handle this thing as I'm to move to my village as my parents stays there so I can start earning & can fulfill my child requirements.