Just wanted to say, wc, that feelings are not just something you "have" or don't have... that's part of it!... but feelings are also something you can create with the thoughts you choose to have or not have.
Illicit sex is always more passionate and fun... remember that is PART of the picture here. There are ways to put that "spirit" of eroticism and illicitness into a marriage, but few couples take the time to do it.
You are in the catbird seat, wc... because it sounds like you could have either one of these women. Your wife definitely wants you, and IF you made a full-court press on OW, I think you could have her, too. She is saying she only wants to be "friends" I know, but that's because right now (in her eyes) your just some guy who doesn't really want her, and is complicating her life with her H. And you are!
Only you can decide who you want to be with. And I TOTALLY agree with the poster who said feelings of being "in love" COME AND GO in a long relationship. Are you SURE you were really fading from your M before the OW... or are you just re-framing your M that way now, to justify your feelings for OW?
Are you really in love with OW, or is it mostly lust? You mention that you wonder if its "really love." I can help you out with that! If OW suddenly turned into a chubby 48 year old who's new religion forbade sex, would you still be interested? If not, wc... it's not love.