Wife playing with fire.... need feedback from similar experiences

[CANDO]

Wife joined classmates.com Got in touch with a few classmates. Nothing to worry about on my part. Noticed more email exchanges from a gentleman including photos. At this point I began to be concerned and talked to my wife about it. Told her this leads to trouble for people. Gets out of hand easily. She assured me it was just a friendship from school days, no interest beyond exchanging life story type stuff. But then she seemed to resent my concern and insisted on her privacy. I said this is not good. Although I'm not my wife's minder and don't need to be in her business, she is putting me in a position of insecurity and suspicion. I stood my ground and insisted she say goodbye and end this before it starts. She agreed but let me know he's married but going through a tough divorce and his mother is ill and she was just showing some compassionate support to him. She relented and showed me her last email to him promising she'd never consider disrespecting her family or her husband. I'm relieved he's in another state. That was all in March. Couple months go by and I discover she'd created a yahoo email account. She wanted her privacy indeed. I know something doesn't feel right. I'm starting to try and find information and just generally have my sensory perceptions on high alert. July comes and now just two days ago I discover extensive texting going on between them. I'm devastated and destroyed. She insists it's only in support of him dealing with his mother's health issues. She cries and says she did me wrong, and I say I can't trust her now. What gives? Anyone go through this before? Women in particular who are willing to share with me their experience.