How to file a divorce petition and what is the cost involved

I Want to file Divorce Petition against my husband bcoz of many Extra marital affair which he has agreed and also given me in written too , saying that he will not do this again but no change he is doing thing again and again and now domestic violence too , i have already filed NC in police station and Sent notice to him for Divorce by lawyer , but he is not leaving the home. i m fed up with all this , i do not want to continuous marriage now.. being am middle class lady i am finding difficulty to hire lawyer due to high cost and their charges for each every meeting. please held me with Divorce Petition charges also please let me know any gov. lawyer or other way which can help me with this