Firstly let me address your "great day". You found someone who didn't degrade you, and actually listened and empathised. I think a key part of surviving and winning this brutal journey, is to have a support network of friends, family or therapists (or a combination of all three). You are not looking to create a club of "Spouse-Haters" who listen to all the gory details, nod in agreement, and give you a sympathetic hug. This is especially dangerous with common friends or family, as this will create a lot of awkwardness if the promised land of a fixed marriage arrives. You are looking for people who will restore your self-worth, make you realise you are a good human being (despite what the WAS so bitterly and venomously says), and therefore allow you to start living. Stick with the therapist, and find others. My biggest support has been through my younger sister. In fact, a silver lining from this nightmare has been how we've reconnected and become so close (I look at our bonding, and keep telling myself "you see good things will come out of this!").
What to do about the emailing? Well my BIL (who's my other big support) likes to use military and sporting analogies, and he'd ask "what's the strategic aim?" and "what's the expected outcome of your actions?" Your aim appears to be fixing your marriage. Will confronting him on the emailing help this aim? I don't think so. It will make him feel suffocated, push him closer to OW, and create tension and conflict. Your husband is not the normal, logical and sane man that you married. That man would not have had the affair, or be rude enough to email in front of you. I'd suggest you show your strength by ignoring the emailing. You can make him uncomfortable by getting on with life around him.
This is really a question of "are you being a doormat and letting him stomp all over you" or "are you rising above the petty things and looking at the bigger picture'.
I believe this is what DBing and GALling is really all about. Ignore the WAS by detaching, and focus on becoming stronger and reclaiming your life.
I'm no expert, and am fumbling and stumbling through life, but I think the people who are most successful at fixing their marriages, are those that appear to truly detach and keep the bigger picture in focus.
Please stay strong and happy, and we'd love to hear more about your budding acting career.
