is it right to file a bigamy criminal case on her ?
The decision conveying her consent to dissolve the marriage by mutual consent would be sufficient as per Muslim personal law which is almost in line with the talaq pronouncement. Moreover, you hav no relief for divorce in the civil court when you have an option to pronounce talaq which is legally recognised in law till date. Further, since you have already initiated process for divorce, her expression and consent for khula goes to say that she accepts your divorce and the marriage contracted by her subsequent to expressing khula, clearly indicates that her marriage was properly dissolved while she married another person after that again, therefore there is no question of bigamy.
one of the accused in 498a my elder brother and brother in law both are in gulf, so whether the 498a will be delayed because of this ? and how to proceed with 498a case ?
Yes the criminal case will be dragged on due to their non-appearance especially for the initial questioning session wherein the charges are being read out.
divorce case still pending. can i approach High court to quash 498a case?
You can very well proceed with quash petition if you intend to do so.
what will be the next stage in 498a after the discharge application on my elder bro and uncle is rejected ? court has given order as appearance of accused on next date.
The accused have to appear before the court on the next date of hearing or else the court may issue non-bailable warrant on them.