Father extra marital affair

My father left us and living together with a widow since a long time,and also he never gave maintenance to my mom.my mom is an employee but as me and my brother grew and also unemployed it is getting difficult for my mom.so my mom approached him last year,he said he has no money and was in debts,so my mom asked to go to the court or give any land to us for a living,he gave.from then on wards he is harassing my mom.he always mentally torture all the family members, He is a state govt employee and also he runs a marriage sound and lighting business ,isnt it an offence to run such thing,as I ask once it is common to run such business and also having extra marital affairs in the village side,i think he can influence the case ,how to file the case against him strongly, we don't want any mediation,nor concern about his career,please do not concern about his career,he is arrogant on seeing his money,please guide to put case against him,it's been a long time but not late,please help,thank you.