1. First being a woman, you have got a right free legal aid from District Legal services Authority. You approach them and they provide you Legal Aid counsel.
2. You need not pay even a single paisa, because being in Govt. service for a considerable time, he was entitled to pension and after private servcie also, by abdicating family responsibility, he must have save huge money. Only indigent parent is entitled to maintenance from children.
3. He failed to discharge family responsibility during his heydays, he cannot claim maintenance. Don't give him a penny and fight him out in court of law. If he is really indigent, Government is providing free old age homes and you suggest him through court to get admittance in one of them.
Don't worry at all.