Defamation case procedure, fee, time limit

A girl's father given written against me to his police station and mentioned that I molest her daughter when she used to go tuition, over phone, by letter using un-parliamentary language by me and posted her inappropriate photo over social media. But I didn't do that. These all are false allegation against me. I used to go office from my house daily. Since 1 yr ago I was talking to her but after that I've no contact with her. Someone else is doing this and un-necessary I'am involved in this. Police came to my house and abuses me and my family and threaten me not to do this again and leave the city as soon as possible. So request you to please suggest me what to do and how to get out of it. Should I file a defamation case against her father for false allegation. We are reputed family in society. My reputation and my family reputation got vanished because of his false allegation. Everyone talking the same thing. We are living in village area. So you can understand how society works in villages. So request you to please suggest me what to do? How much time it will take to final decision because I'm unmarried, Male. How much fee I've to pay??