Breaking engagement after 1 month of engagement

The marriage was fixed in feb'18 and engagement is conducted on 18 June 2018. Then I and girl was talking over call and whatsapp. Everything was fine. But on 22nd July 2018 I found that the girl was telling False from starting. Some points are as mentioned: 1. Girl informed me that she had gone to movie and thereafter to bar and café with her friend Sakshi and Mama Mami. But later I came to know that she was celebrating her boyfriend’s birthday in late 12 midnight at café. When I asked her about this, first she told me that she didn’t hide anything but when I send the pics then she told it was planned by her friend Sakshi. Then I showed the video of live concert which both had uploaded but in two different date. But the girl was telling white lie that the video is different. 2. She told me that she goes to library every evening 7 to 9 PM. But when I check all the details of the library which she told was false. Neither She know the fee nor that books are available or NOT. She lied about library for more than a month. During this period she didn’t replied to my whatsapp nor the call. Her reply come next day aftet 10 AM. 3. When I checked the timing of her Boyfriend, his office timing was from 10AM to 7 PM. It seems she had lied many things to me. The main point is that she even didn’t accept her mistake and firm that she will do what she want. So, this nature is NOT suitable for both of us for long run. So, for that I discuss with her family. They were taking girl’s side and asking me what to do. Meanwhile girl also call my parents and given false allegation that I was disturbing her for last 2 months and many thing. I discuss with my family and they discuss with girl’s family. Both family mutually discussed that if both Boy and girl is NOT happy then marriage should be cancelled. But the Maternal uncle of the girls call my family and threaten them that they will come to negotiate. They also influence girl’s parents, and now they want us to think. They called me, but I asked them to discuss with my family. Now they are NOT receiving my parents call. Also there is till now no any negotiation call we receive. They have transferred some amount for girl’s purchase which we return to their account. Now also they are NOT receiving the call. Kindly suggest if they can file any case to us? I want a polite and smoothly end for both family without any society humiliation. Regards Kunal