Premarital sexual affair

One year back i got married then i came to know that my wife is having an sexual affiar with other guy. I did not know about it earlier. Recently he came to know about my wife's premarital affair with other guy and I asked my wife she accepted i had relation before marriage. She is not at all good even after marriage. I lost hope on life. I dont want to live with her and want divorce from that girl. When i and my family talked about it with the girl's family, they accepted for divorce and ready to give my marriage expenses alos and took her to their house. After no response from therefore i went to her house and i am shocked situation there. They put lot of fake allegations regarding dowry, torture, domestic violence, so on. These all are false allegations. Just because that girl is characterless, they are putting these allegations on me and on family. They are try to asking for lacs of rupees otherwise they are command me that I have to be with her their home only for two years. I have video and audio evidence which they are accepted also. I want to know what i can do in such situation. I am in unbearable situation and mentally disappointed because of these things. I can't understand my future now I am 33 year old. Can you please provide any solution for it. can i be helped and get out of this difficulty. I didn't understand why premarital sexual affairs not ground for divorce how can a husband bear it he is human being he also have emotions why law against to men? Please help me..