how was the behavior of your wife towards you. Is she behave more lovingly ,give proper care ?Do you have any other issues in your married life with her , if so you take it as serious. Trust is an important thing is a married life. The deeds of your wife (if your version is true) is not admissible one.Definitely it will made much worry on the life of a good husband.
Even though it is not a good admissible proof ,you will approach a good private detective agency and check her future movements through face book ,whats app ,face book,messenger,yahoo chat,immo,skype.If she has an affiar she will contact her alleged boy friend again and you all collecting evidence for your divorce petition.
The better suggestion is , After getting more evidence you should take a decision about Divorce . The present evidence she denied and explain the circumstances of denial. So when you approach the court try to show the mental cruelty this evidence does not help you. You will wait for more evidence and silently watch her deeds.