Husband not abiding by transparency rule, what to do?
My husband and I have been poly for a few years now. Earlier this year, we had a situation with someone he dated a handful of times, I'll call her Mary. She failed to disclose a sexual partner she had before she had some limited sexual contact with husband. The partner she failed to disclose, I'll call him Mike, turned out to be high risk. (Mike was having casual sex without condoms with others. Mary claimed to not know this for a time.)
Even though husband hadn't actually done much sexually with Mary before Mary admitted that she was sleeping with Mike, and then, later on, disclosed Mike's high-risk behavior, I considered that the simple fact that Mary did not disclose the existence of Mike, when she otherwise knew husband very well and had been forthcoming about other partners she had, a breach of trust. She had been willing to have sex with husband before disclosing Mike, he was the one who decided they should wait, and we only heard about Mike's existence days after that, and over a month later, about Mike's high-risk sex life.
I told husband I did not trust Mary as a potential sexual partner for him because of her failure to disclose and poor screening process for partners, but that I was fine with their continued friendship. Mary heard this, freaked out, and dumped husband as a friend. What I knew was, he had asked her to reconsider that, he had really, really liked her, but she wouldn't talk to him.
This all happened about six months ago. I just found out that husband and Mary have been corresponding at length, in secret. Just emailing, I don't think they have seen each other. He knows I am not one of Mary's biggest fans, but he also knows that I am OK with their nonsexual friendship.
Transparency between us has always been a written part of our rules. He knows he is supposed to tell me when he is talking to someone new, or reconnecting with someone significant from his past. And yet he has been keeping this a secret for weeks. This upsets me a lot because we are just getting back on track in our relationship after he broke a promise he made this summer (with a different partner), and compromised my trust in him.
Do I confront him now? Do I wait until he actually sees her behind my back, if he does? I don't get why is is hiding this, he doesn't even have to.