Wife torturing husband & his girlfriend instead of divorce

Hi, I am in a relationship from last 2.5 years. My Bf is married & having son. His wife knows about our affair, but rather doing any legal activity she only use to do blaming-and abusing me time to time. Even she tortured my parents & my BF. Blackmailing on small small things. Just because of he is in extramarital affair he couldn't say anything. So many time I found that she want divorce but don't want to initiate. Before few month unfortunately i have given all the proofs which were enough to proof our affair, but still she hadn't taken any action. My BF is not ready to confess our affair, Because he don't want to loose child custody but at the same time he wants to marry me. And both are they don't want to live together but instead of taking action accordingly just waiting for each other's fault so they can blame, this divorce happen only of Yours fault. What we (Me & My BF) can do so that we can get his child custody & also divorce from that lady. Please suggest (Hindu Religion)