MB - hijacking Rain's thread for a second - the OW has nothing, absolutely NOTHING to do with you. Your H is using her to pander to his fragile little ego. You are absolutely correct that she is not getting the "real" H. The real H is gone for now. Buried. He's looking for "happiness" in the one place he's not going to find it.
OW is as broken, if not more, than he is. What kind of woman is happy with another woman's H? Not one who has any sense of self-worth. Say she's the sick kind of OW? The one who feels like she is "winning" by stealing another woman's H. What exactly is she winning? Someone who cheats. A moral failure. Someone who will bail on his wife and kids for the momentary thrill of being with someone he feels superior to; because that's what this is all about. H is using her to feel better about himself. He knows he's a failure. She makes him feel better about it.
This is going to sound really odd to you - but you should feel sorry for her. She is lost, lost, lost. She has no self-esteem. She has no morals. She is out to get what she can, probably thinking that there's money and security at the end of this road. She's going to wind up with ashes. She is so broken, she can't see the obvious. She is likely damaged beyond repair. I feel badly for her. I can't imagine having so little value for myself, I'd be happy with something that was never mine, and never will be. Let some man use me, so he can feel better about himself, a loser? No. Not going to happen. I'd rather be single. Those of us with any sense of self-worth would rather be single than be used.
You are torturing yourself for no good reason. It has nothing to do with you, and everything to do with your H's self-hatred. Let it go. Stop thinking about it. Put your focus squarely on YOU. Stop playing the comparison game. Your H is playing a role for her - one that doesn't exist.
You need to detach. I wish I could tell you the secret to getting there. I do know the way to start...and that is to force yourself to stop thinking about him, and start thinking about YOU. How much healing you need. What can you do to distract yourself? There is a website called the stages and lessons of midlife that could teach you so much. Just google that name, and it should turn up.
The woman who runs the site has been through this, and generously shares what she's learned about it with the rest of us. I found answers and healing there. A lot of what I share with you, I learned on that site, and implemented in my own life. It made a difference. I don't think about OW at all. She's nothing to me. She is a victim my H used to make himself feel better. That does not make me proud of him. Better her, than me, though. I have no desire to be used. Ick! I have way more self-worth than that.
Think about what I'm saying - you have got to stop yourself from going down this path. Nothing good will come from it, and you owe it to yourself to bring good into your life. You're the only one who can right now.
