This is tricky territory and I would take some time, take in the advice here and look for threads that talk about this kind of sitch. Maybe check out the affairs section.
I would not be quick to communicate with OW...I would look more for how to communicate with H. But, I'm not sure. I have an H who has rationalized having so many female "friends" that I think he was immersed in multiple EAs. I don't deal with that right now, I deal with what is in front of me. But, there are people who have successfully navigated these sitches and yours seems to be pretty fresh so wait a little and see what advice you get.
