Save my married life

What will the law says" if a married person without divorce has a illegal relationship with a married woman (age 50)" I was married with my husband in 2012, and we got boy in 2014. My husband had developed frienship with this lady at college time. This lady was already married and living with her husband and daughter. Her husband was big bussinessman. she had knowledge of our marriage and also about my children. My husband has provided sorts of facilities according her demand and have given rupees for jewelry and clothes because she was demand as a friends so that he provide all things which costs no calculate anytime. Now that lady is sending illegal photos of my husband social sites but after mutually said please i m not interested in this relastionship and after that she harassing my husband for more money. I had also offered her that she can live with her husband and lead a life. She clearly says that she do not want husband, but she needs money. Please tell me and my husband that how can we come out of this problem.She is misusing the circumstances to her advantage and is also equally liable for the illicit relationship.