Report this to the police station of your area, and lodge an NC of threat and criminal intimidation by her parents.Please mention in the complaint that her parents demanded 25 lakhs and asked you to pay and end the marriage. This would help you in the court if you file an independent divorce as wellas if they gpo whead with a498A or domestic violence.
Immediately send a legal Notice asking her to return in short time as she stays away without any reason deserting you of your conjugal rights and warn her of legal steps including divorce proceedings. if not responded go ahead with the divorce petition on grounds of cruelty. Though there is an option to file RCR, if you do not wish to bring her back it is better to proceed with divorce.
Regarding her threat, you do not have to agree for their demand .
In 498A you will get anticipatory bail, and in case she files a 498A, that itself can be made a reason to ask for divorce.Courts are also taking a lenient view in favour of husbands and in-laws as it is a threat in the form of 498A which is mostly misused by wife's as a weapon against husband and in-laws to extort money.
If she files for a domestic violence case you should defend as there is a good chance the court order maintenance if she is not earing.