What does this mean when your wife says...?

I'm currently away in Iraq on deployment for the Army. Me and my wife bicker here and there just stupid stuff mainly because the distance is tough, but never anything too serious. We've been together 5 and a half years and things have been rocky but never to the point of separation. Today shes acting very defensive and weird and is being unnaturally mean to me. Shes having conversations with guys on facebook and other little things. So I ask her to see her facebook pword to see if she has anything to hide and she gets super defensive and leaves, later comes back and I question her if shes having feelings for another guy and she keeps saying its weird I don't know. She leaves for work then later comes online and says I'm sorry its just I think a client at work is hot and its getting me confused, I don't talk to him outside of work I promise. What should I do?