He's also ended the R with OW too, he's still in contact but tonnes less than he was and its dwindling - that in itself is a huge step in the right direction.
That is huge....but I would be looking for him to cut all contact with her. As long as he has some contact with OW, there'll always the risk that they'll fall back into it. Unless you set it as a boundary, he'll probably be of the mind "we can still be friends" or "its ok as long as I don't sleep with her." People tend to convince themselves of ways to keep that door open.
I don't know if you've read my story, but that's basically what happened to me. Crib notes version: W decided she didn't want to be D'd at the 11th hour, and the only boundary I set was NC with OM. She made it 2 weeks before she fell back in with him, at which point I signed the D papers. Post D, W again decided she wanted me, but continued to work with OM....each time I discovered she was still breaking my boundary, I went further and further away. After I stopped sleeping with her, she fell back into it with OM, but continued to tell me she wanted to R....but she never cut contact with OM. About a month ago, she again tells me she wants me, but yet I know she is still seeing OM....now I'm NC.
My point here is that an EA/PA really is like an addiction, and you can't keep that person at arm's length and make your M work. They have to be removed from the equation completely.
