1. Evidence has to be independently gathered by the aggrieved spouse by hiring a detective agency.

2. Unless the evidence is such which would demonstrate that in all likelihood the spouse had intercourse with someone who is not his wife, the court cannot dissolve the marriage on the ground of adultery. 

You may engage some detective who may collect evidences for you. Also try and talk to him through messages and whats app and keep record of such messages which may show mental cruelty.

regards

Yes custody can be given to you

Yes such message will help you in divorce case

Romantic messages do not prove adultery.

1. If the wife starts residing separately from her husband and the children follows their mother then there is no question of seeking their custody from court.

2. Only if the husband refuses to allow them to go with their mother then only the question of custody comes.

3. In custody battle the court given pirmacy to the opinion of the children if they have enough intelligence like children of of such age as yours.

Better engage a detective agency and gather evidence of husband extra marital affair 

2) messages exchanged between husband and other lady will help you in making out a case 

3) audio recordings between husband and lady will help in seeking divorce 

If children want to stay with mother court can award you custody of your children 

you can also seek maintenance for yourself and children 

romantic messages would help you in seeking divorce 

You can file contestsed divorce against her.  You need do spy her or appoint detective,  cctv or software in her phone to get evidence

See evidence from private investigator as such are not valid you need to get proof of his relationship and physical relationship like there stay together you can copy messages from his phone any photograph hotel bills.

Since the age of children is such that they can understand with whom they want to stay so court can ask them in the custody matter and if they are willing they can stay with mother.

Yes grounds such as cruelty and adultery can be taken for divorce and all other evidence along messages can be placed.

If you have audio video recording or WhatsApp chat conversation then the audio and video recordings are considered as evidences as per the provisions of indian evidence act .you can file divorce on ground of adultery or creulty. 

based on affair divorce can be granted by the Court. by spying or by any detective or any app, the massage or pics can be admissible in evidence as per section 65 B of the Evidence Act-1872.

custody can also be granted to mother if proved that husband is having affair.

as the children are 17 & 14 so their consent will matter in the court.

Feel free to Call   

1. Custody will surely be coming to the mother, if she is not at fault or adultery.
2. As children are also of that age wherein they can also be asked by the court of law about their choice or residing with whom.
3. And husband would have to give maintenance for the children and for wife also if she is not working.
4. And yes, you can hire a detective to collect the evidence for his adultery, this is not illegal in India.
5. Romantic messages may be taken into account, but would advice you to have something in which he might be going into little more intimacy talks.

What will you be able to do even after establishing his extra marital affairs with another person, because you cannot take any legal action on it since it is not a crime.

Except for divorce on the grounds of adultery you cannot take any action on this even if he is admitting himself of this affair.

Instead you can live separately from him if possible by filing a petition for judicial separation on this grounds so that your marriage can be in tact and secured.

Since he is maintaining your family properly then you can be cautious while initiating any legal step on this.

First the mother should convince the court about this and also should train the children to speak in her favor before court at home itself.

The court may accept the evidence of the grown up children

The romantic messages or any other audio recordings may not be considered as admissible evidence in court of law for deciding the subject issue pending before the court in this regard.