Since you caught her in compromising positions pics, then try to show that she is living in adultery. It will make the prosecution's case fatally weakened.
Mostly in the court the allegations made in the 498A are proved false as the witnesses are partisan or interested witness.
Mere allegations of asking money/dowry will not suffice, there should be incidents where witnesses can state that she was forced out of the house, if she was beaten up, any treatment or medical consultancy papers, NC lodged of the incidents etc. Onus of proof rest on the prosecution. If a wife makes a statement that she was beaten up in your cross examination you should ask her whether she filed any police complaint in this regard, did she visit any doctor for medical treatment, wife alleges dowry was demanded whether any police complaint was filed of dowry harassment? How was the alleged sum of Rs 1 lakh given? Any emails / letters on record wherein such demands were made? If you don’t cross examine on these issues evidence would go in uncontroverted
As per Section 4 of Section 125 of the Code, “No wife shall be entitled to receive an allowance for the maintenance or the interim maintenance and expenses of proceeding, as the case may be, from her husband under this section if she is living in adultery, or if, without any sufficient reason, she refuses to live with her husband, or if they are living separately by mutual consent“.