I guess some of us have a question that was not mentioned...
1. Do you want to stay married to your W? It seems as though your post focuses on the OW, but you make no menion of your W and how your marriage is now?
I think you need to seriously think what you want to do with the situation you are in. I know you seem to think you have deep feelings for this OW, but as so many have said, you are in a relationship with absoultely NO responsibilities of real life. In my opinion, this is one of the things that make A's so appealing to some. Allows them to live in a fantasy...
Unfortunatly, Fantasies are not reality, and people come crashing into reality once they realize what they have done.
You need to stop focusing on the OW and really start focusing on your W and your M.