I think a lot can be happening that we don't know about. She could be cheating, but she could just as easily be fed up with OPs overreactions that started from the very beginning when she wanted to get in touch with friends.
Communication is the key word in this instance and it's definitely missing. The wife needs to find a way to communicate her needs, be upfront about what she is doing and explain what she wants to fix if she wants to stay in this marriage. The OP needs to be more understanding and empathic and not fly off the rails every time something 'unlikable' happens.
As well as counseling I would recommend (for both) to do a communication class or pick up a few books on conflict resolution.
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~