Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...
My take is that because the contact was with the OW and was done without your advance consent, it could rightfully be considered a transgression of some nature. Of course, the question of where his business ends and your business begins is a question for you two to answer, and it is not the same for every couple. The bottom line is that you need to be respected, and in a marital relationship that isn't open, respect cannot be had without being truthful about other relationships.