I wouldn't blame you at all for having trust issues at this point. I think it's normal for some people to keep in contact with exes, but the married guy she had an affair with? I mean, come on, how can she not think that this is not crossing a line at all?
Entering into a new relationship means cutting certain ties, especially ones that would make a new partner uncomfortable. The fact that she lied about it is a sign that she knew it would be a problem for you in some way, but chose to do nothing about it. Unless she was withholding it out of mere cluenessness, in which case she has a shaky grasp of human nature. She has now come clean about it and showed you the emails, so that's a very good sign, but it could be too little too late for you because part of earning trust is coming clean about things in the first place.
Whether to continue to trust her or not, is completely up to you. Her dealings with him could be completely innocent, but if it bothers you, this is your comfort level we are talking about, not anyone else's. Sorry I couldn't be more helpful, but I do want to mention that I do not think the problem is your insecurities.
Last edited by starbuck; 22-01-10 at 09:08 PM.
“Inside every cynical person, there is a disappointed idealist”--George Carlin