See since wife has filed a divorce on ground of cruelty and you also want divorce from her there are two options either you ask her to settle and take divorce on mutual consent and ask from her custody of the child. Or you have to file divorce against her on ground of adultery and further file custody for your daughter on ground of welfare of the child and adulterous nature of mother.

Appoint a lawyer. I'm prepared to offer my legal services. But first exhaustive consultancy is required. Kindly provide me your email id/phone number so that I can get in touch with you. 

1) You can file for Divorce on adultery ground and custody of daughter will remain with her as mother is best care taker of her children. Till your daughter became 18 years old.

You need to file a divorce petition in family court. You need to file the custody Petition along with the same

Dear Client,

Do you have proof of her adultery , if yes than file divorce on the ground of adultery and application of child custody.

Mere allegations of adultery is of no use until prove by cogent evidence.

You can file for divorce on grounds of mental cruelty and adultery 

2) gather evidence of your wife extramarital affair 

3) seek joint custody of child 

4) wife guilty of adultery is not entitled to maintenance 

With all available proof, you can counter the case. Also unfit parent category, claim custody of  your daughter.

Dear Sir,

The following information may kindly be read.

Divorce Without Mutual Consent: In case of a contested divorce, there are specific grounds on which the petition can be made. It isn’t as if a husband or wife can simply ask for a divorce without stating a reason. The reasons for divorce are as follows, though some are not applicable to all religions.

1. Cruelty
   Cruelty may be physical or mental cruelty. According to the Hindu Divorce Laws in India, if one spouse has a reasonable apprehension in the mind that the other spouse’s conduct is likely to be injurious or harmful, then there is sufficient ground for obtaining divorce due to cruelty by the spouse.
2. Adultery
   In India, a man that commits adultery (i.e. has consensual sexual intercourse outside of marriage) can be charged with a criminal offence. The wife may, of course, file for divorce as a civil remedy. If, on the other hand, a wife commits adultery, she cannot be charged with a criminal offence, though the husband can seek prosecution of the adulterer male for adultery.
3. Desertion
   One spouse deserting the other without reasonable cause (cruelty, for example) is reason for divorce. However, the spouse who abandons the other should intend to desert and there should be proof of it. As per Hindu laws, the desertion should have lasted at least two continuous years. Christians, however, will not be able to file a divorce petition solely for this reason.

What about child custody?

Many assume that the mother always gets custody of her children. This is not the case. While the courts usually agree to the decision of the parents in a mutual consent divorce, the courts are expected to see to the best interest of the child. In a contested divorce, the courts will examine the ability of the mother or father to be a parent to the child, for example. Money is not usually a matter that is considered. Non-working mothers are regularly given custody of their children, but fathers are expected to provide financial support.

See what's app data is encripted so you won't be able to get the details of same. Further call list from the Airtel can be obtained with order of court.

Along.call records you need corroborative evidence such as picture or hotel records to establish that they were.in physical relationship.

You have to prepare transcripts of your conversation 

2) enclose it to your divorce petition 

3) you cannot rely upon audio recordings between your wife and her lover as it would be infringement of her privacy 

4) mere call list does not prove adultery 

the audio recording is acceptable as an evidence in the court, but in your case the recording is quit old so may be it is not possible. 

You can file divorce on the grounds of desertion but it will take 2 to 6 years..  For fast and hassle free divorce you have to file mutual divorce under section 13b . But both spouse want to file petition in mutual divorce , you may get divorce decree in 6 to 18 months. 

Dear Sir,

Please put the following in the browser and get the relevant matter.

RECENT TRENDS IN RECORDING AND ADMISSIBILITY OF EVIDENCE TOPIC:- APPRECIATION OF EVIDENCE RECORDED THROUGH ELECTRONIC MEDIA. Prepared by Sri.P.Rajendra Prasad, Addl. Senior Civil Judge, Srikakulam.

1) For additional evidence you can gather as much as possible you can gather it list call list and whatsapp data through court.

If she has filed the divorce case, then you have to challenge her or if you have filed it  then you may have to pressurise your lawyer to hasten the matter, in any case it may take at least two to three years for disposal.

For child custody case, you may have to file a separate case seeking child custody and for visitation rights as an interim relief.

Dear client.. if u have proof to prove that she is involved with other guy.. then definitely it will help Lott.. 

And u can get divorce along with child custody...

The audio recordings even if proved by invoking the provisions of section 65B of Indian Evidence Act, may not be admissible as evidence until she confirms that it was her voice and she admits the contents .

Airtel call list will not define her adulterous acts.

Dear Sir,

Supreme  Court supports divorce on the allegation adultery by wife. You need not prove it 100 percent as it is known secret act. You will child custody as wife living in adulterous life. You need not pay any alimony to her.

Call history can be arrange but court will not summon it, you have to make effort for it. Audio recording good but sufficient to prove adultery. Whats app data is encrypted, cannot be traced.

Yes. Take additional documents like Airtel call list and duration, WhatsApp data also considered as legal documents

You will not get call list unless the mobile is in your name. WhatsApp data you will not get at all, as it's not stored anywhere.

Audio recording is not sufficient.

What notice did she send?

Since your daughter is 6 years old, file the case and drag it for 2 years. When she is 8 years she can choose whom she wants to stay with.

Negotiate during mediation. That's the quickest way.