Extra marital affair, wants divorce.

I am 34 Years women having a 6 years daughter. Now after 8 years of my marriage, I have come to know that my husband is having an affair with a women having 3 kids and elder than him. It may be possible that that women's youngest son is from my husband, I am not sure. My husband is a Pharmacist. I do a Pvt. job in a school. He is alone son having all property and house in his name. I want to know what should i do to get him caught in law's hands, what should i do to protect my interest in the property and future of my daughter?