Widowed father in law committing adultery

Continuity of prev - I realised that I have been cheated. What ever the respect I held for them all went to gutters. My father in law kept on accusing my hubby infront of me for no reason. And wanted me to support in accusation too. But I loved husband then so o couldn't. They fought every day and made a judge. It was hell. Eventually I went into depresson and fell pray for migrain headaches. Fil kept on saying that u r staying here for free. Get out of my house. U don't deserve to live in this house. And started blaming me too saying I. Not serving him well. How can I serve well a person who always treat ur husband ill. Moreover he always disrespected my parents when ever they visited and requested favours from me too. Finally after a long struggle we moved to different house. Now we got hold of some audio recordings of both widowers intimate conversations which proves that they are having illegal relationship. What should I do here. (My fil always boasts about how righteous he is)