Vishakhaji,
My advice to you is that you can and should file DV case against the husband. You can file this case one and half a year after separation also. In this case, you can ask for maintenance, shared household, protection order etc. If you have children, their expenses also can be recovered from him. Staying for the last one and half year away from matrimonial home points towards domestic violence perpetrated against you in the matrimonial home, before you leaving that place. So, there is a valid reason for you to stay away from him. Just physical abuse is not domestic violence. In the Act, domestic violance has been given broader descripttion. His having a relationship outside the marriage is itself a "psychological abuse" and it demeans you before yourself. The legitimate wife in such situation always ponders that "what I am lacking that the other woman has?", forgetting the fact that some men without excuse develop physical relationship with other women, subject to availability of opportunity. This thought predominates the mind of the wife and if it is not a psychological trauma, what is that you would call a psychological trauma?. Similarly, spying the wife or attributing wrong extra-marital rlationship to the wife are also mental harassment and come within the definition of domestic violence, even though these facts are not there in your matrimonial life.
Now one argument is put before all the harassed women, whose husbands have extra marital relationship. As the marriage has alredy been broken down and as he is infatuated with some other woman and there is no scope of restitution of marriage relationship, why pusue the court case spending thousands (lakhs) of rupees on advocates and spending long years in court corridors foregoing mental peace without having any substantive result. So go for MCD by accepting a lump sum amount and allow the husband to do whatever he likes and try to find out some other man who suits your mentality. Such arguments discourage the erred and harassed innocent women to claim their legal rights and the real culprits get away doing whatever illegality they do by flasshing some currency on the wife and severing the relationship at the fall of the hat. Such continuous arguments also attempt to make the DV Act, Section 498-A and Dowry Prohibition Act ineffective, and such arguments, did not ever convince the judges and the judges dismissed all those cases where the constitutional vires of these Acts were questioned.