I hate to say it but I'm just as leery as NYS here. Obviously I wouldn't press him on keeping her as a friend right now. However, in my opinion, I can't see how he could come back, eventually have you two back 100% and still have her as a friend.
In a couple of the books I read (including "Surviving an Affair" by Willard F. Harley), it is recommended that if and when the LBS wants to come home from the affair, many things must happen or it just won't work, such as:
1. He must sever COMPLETELY from the OW. 2. Change e-mail address, cell phone #, your home phone #. 3. If they work together he needs to transfer or find another job. 4. Carry a phone or pager just so you can reach him 24/7 (sounds harsh, but hey it's his job to do whatever it takes to help rebuild your trust.
There are others, but I'd recommend getting the book. There's good stuff in it for someone who is at your point in the game.
Take it all for what it's worth. I just think that if it was me in his shoes and I was truly committed to coming back to you and making a go of it, I'd be on my knees, apologizing profusely and wouldn't even think of putting out there an "I want to come back but I don't want to hurt "her" so I'm going to take my time. You just have to bear with me on that. Oh yeah, also, I want to stay friends with her too. Is that OK?" It just don't sound kosher to me...
I hope you don't take that as just me knocking down your hopes, it's just that it takes a lot more for me to buy in.