Husband has ex marital affair - on behalf of my friend

My friends husband has an ex-marital affair past 3 years. Now he as confronted to my friend & wants to divorce her. This lady does not have anyone to go back to as her parents has passed away. she also has a daughter age 8. Earlier her Mother in law supported her, but lately she also no more supports her & makes her do work all day in house like a servant. Husband has stopped giving monthly money for house hold expense. His condition to Mil is to throw his wife away & only then he would give money at home. She is been taking all the non sense to save the marriage. But now she feels nothing is working out. Also husband is threatening her that he will not give a single money to her as maintenance. Maybe he will take away kid frm her showing her bad mom. she has no job !! Pls advice how to handle. Also is there any adultery law where the other lady gets a lesson !! pls advice how she can have a secure life , if she has to leave him. What are her rights to claim a house. I would appreciate advice at earliest.