You can sue adultery if your have strong evidence. You have to collect all call records from mobile company. You might investigate on this with either yourself or close friend whom you trust or any detective agency and get strong evidence on this.
Though it is very hard to prove, But if you can prove this then you also can get divorce as per sec. 13 of HMA.
497 IPC. Adultery —
Whoever has s*xual intercourse with a person who is and whom he knows or has
reason to believe to be the wife of another man, without the consent or connivance
of that man, such s*xual intercourse not amounting to the offence of rape, is guilty
of the offence of adultery, and shall be punished with imprisonment of either
descripttion for a term which may extend to five years, or with fine, or with both. In
such case the wife shall be punishable as an abettor.
CLASSIFICATION OF OFFENCE
Punishment—Imprisonment for 5 years, or fine, or both—Non-cognizable—
Bailable—Triable by Magistrate of the first class—Non-compoundable.