Appeal against divorce decree

My husband filled a case against me for divorce on Ground Of Cruelty. My father in law was the only witness from his side to prove his allegation no other evidence or witness was given from his side. During my witness just I told judge that my husband is having multiple affairs and screenshot of is conversations with a married lady was also attached as a evidence. But petitioner In his petition did not take this ground as cruelty neither during witness he told in his statement during witness. Neither his lawer during my cross examination raised this issue to me. Neither 2 witnesses from my side my dad and aunt accused him for this. Only I gave a statement in my witness though what I stated verbally was 100% true but failed to prove the same except those screenshot I had no other proof. My husband and I after marriage were kept in a separate building after marriage I used to go to in laws building only to perform my household chores. I was not allowed to enter any other rooms. Two buildings are not very close even if one shouts in one building can not be heard by the person in other building even then my father in law came to court to witness few incident which never took place all allegations filled by them are baseless and false. My question here is judge gave decision against me by giving weitage to my father in laws statement though my father law was enable to answer the exact date month and not even year of when few major incident of cruelty as per mentioned by them took place though my period of stay in matrimonial house was just 1 year only how can he forget year. This was only because all stories are concocted. Judge further stated that I had stated in my witness that my husband is having multiple affairs amounts to cruelty. Before case and even during this case and till date I have never accused my husband publically nor privately for the same I always kept this secret from my family and his family. But only after this case I admitted this to my parents and my lawyer I was not in a opinion to file this in my reply so I did not file this in my reply but my lawyer insisted me to attach those chats just to bring facts in front of court so I had no choice left as he told me this will make my case strong. In my husband's counter reply he made no objection on those attached chat either. During my witness my lawyer again insisted me that since I have attached this chat as evidence I need to point out this in my witness so I pointed those chats. But this has turned against me as judge in his statement statement has stated that this amount to cruelty. Though this ground was not taken by petitioner in his petition because he knows those chats were true. I want to appeal against judgement what shall be my points to be highlighted to turn over the judgment.