Seeking remedy against father’s adultery

Hi, My father is 73 year old. Since his youth he was involved in extra marital affairs and always was interested in Ladies like Maid, colleagues; lady peon; or neighbour or any lady with whom he can do some sort of mischief. My Mother is in deep agony for what her husband is doing and now her stress level is reflecting on her health also. My Father has keep a lady in one of our house which was earlier supposed to be let-out for tenants. My Father at this age doesn’t have any sham or respect for society. In my knowledge this is 8-10th attempt where we have caught him in doing adultery. I have suggested my Mother to divorce him but at age of 65 she says it will be shameful for her etc etc. He is such a shamless creature that after all such incidence he will stay in My house and go out does all adultery, Rome around late night and be back whenever he want. We keep on tracking him for his wellbeing and more over because of my mother. Pl suggest how can I handle this man, rather I want some action within law against him.