1. It is against the Advocates Act to settle a case against taking money.
2. You should directly establish contact with your wife and amicable settle for MCD against agreed terms.
3. Thereafter ask her to execute an Affidavit affirming that she had lodged the said police complaint u/s498A of IPC under domestic rage and both of you have settled the matter now amicably and also that she has no further complaint against you.
4. The 498A case has already started and Charge Sheet has been filed. The Court has ignore the jurisdiction issue. Actually the police station of Kolkata should not have registered the FIR u/s498A of iPC since the cause of action has arisen at Coimbatore.
5. Since the charge sheet has already been filed, it is the fit time to get her executed the said affidavit as stated above and then file a petition before the High Court u/s 482 of Cr.P.C. praying for quashing the FIR based on the affidavit affirmed by your wife and at that time your wife also should support your said claim preferred before the Court.
6. If she is not agreeable to settle the matter amicably, contest the cases fittingly without resorting to such practice of making deal with opposite side lawyer since he can double play his game for which you might incur loss finally.