Firstly, a person needs to be strong and brave enough to face this situation. Getting cheated by a partner harms a person not only emotionally but mentally, it causes a serious depressive mindset because of which the person starts mislaying his senses to understand and differentiate one conception from another.   
 
The Indian Penal Code:
 
Section 497 of the Indian Penal Code states that if a married man keeps a marital affair or physical relationship with another married woman then it charges a fine or imprisonment (or both) to the man whereas a woman sets free. The man\’s relationship with another woman is a crime against the other woman’s husband not his own wife. This kind of activity is known as Adultery and exempts the punishment for a woman while the man gets to be punished.   
 
The above statement clears that whether a man is in a physical relationship with another woman or he gets cheated on by his partner, the punishment is implemented for a man, not a woman. Although, this is no more a criminal offence in the constitution whereas the records have been kept on the ground in case of divorce.  
But, what you can do?
Although there are lesser laws for men in Indian Constitution, there is nearly zero per cent chance that you can get supported legally. But, fortunately, there are ways you can deal with this situation at your end.  You can play two cards here, one might be in your favour and the other one might be against you. Here are two things, either you can communicate with her, explain to her how broken you are feeling, and give her a second chance to gain your trust back or you can simply leave her and ask for a divorce as you are really hurt and do not want to be in this situation again. 
 
The situation you are in is a real-time heartwrenching and depressing situation which might hurt you mentally, you can file a divorce if you want to get rid of this relationship and want to start a new journey.   
 
You should take your time, understand everything, and then take a step ahead as you feel to be done or happen.