Hi Love, I haven't posted or responded to your thread for quite some time, but I've been following your story very closely and want you to know that I think you are absolutely doing the right things.
I'm farther down the path in my sitch, but our sitch's are so similar it's like I'm reliving every moment through you. It's been over a year since I find out about OW. Since then, H has moved out for 6 months, I'm 4.5 months pregnant (with H's baby, of course), and he just moved back home 2 weeks ago.
We went through exactly the same things you are going through with OW...he was getting closer to me, we ML often, he started warming up to me again, but at the same time he couldn't let go of her. I think in the end, by letting him start to see the real her and without my interference, her immaturity started showing through and he realized what he has with me is a lot more real and lasting.
The picture he painted in the beginning of the perfect woman turned out to be a lot more flawed than he let on. At first he told me they were like soulmates...instant attraction...had so much in common...she made him feel good when he was with her. In the last few months I found out she had an abortion when she was 19, has ADD, was a horrible student in school, smokes pot, etc. She was trying to make him jealous this summer by dating other guys (when she turned 21) and she would text message him with all the gory details of her dates just to hurt him.
He moved back home 2 weeks ago, changed his cell phone number because she was still text messaging him, and now he wears his wedding ring to work every day (she still works with him). I can't say all is blissful now as we have a lot of work to do, but it sure beats the situation 6 months ago!!!
Hang in there...I really think you're doing the right thing and this thing with your H and OW will fizzle out eventually. It may take some time, but it sounds like he is already starting to see some of her flaws and realizing that the flaws he thought you had are a lot less important than he originally thought.