Family wishes to separate from Dad due to adultery. Want to secure our house.

My dad has always harassed my mom since the beginning or marriage. Physically and emotionally. Their marriage is now 50 years old. We recently found out that he has been cheating on mom for past 15 years. Mom went through a lot of trauma and self-harm behavior also. Since dad is 70 years old we asked him to stop all this and we were okay to forgive and keep him in the house. But he kept on lying to us for 9 more months everyday and never stopped it. Our house is on his name. We want to secure it as it is our only house and we have reconstructed the entire house on our money. We know that he isn't going to give us any share in property or pension. We tried going to police and NGOs that help women. All spoke to him. He agrees on their faces and backs out on his word. Is there any other option left without legal proceeding? If not, what will be the best way to secure the property and get separated from him? Which case will give us the most benefits and be more likely to win and secure the property? What is the approximate cost and duration that will take in the best suitable case? What happens if we lose the case or if he refuses to come for the hearings? We don't wish to stay with him but we want to secure our house.