I wish I had some decent advice for you. I guarantee that one day your H will realise what an idiot he is because deep down he is a good guy but his behaviour in this is intollerable. I think there is only one suggestion I can make and thats to send him to the naughty corner. This is entirely my opinion and if you choose to do it will be very hard but you need to "act as if" but also withdraw priveliges. You will need to detach some doing this and it may get ugly for a bit . Stop being his wife , treat him like a lodger , dont do his washing or other stuff you might do. When he calls you on this , and he will , tell him while he has inappropriate contact with OW then he clearly does not value you as his wife and you are no longer prepared to act as his wife in the circumstances.
Anyway just an idea and its a bit radical , would take determination as well and is not without risk .
