I just wanted to let you know that other people here are going through the same thing. W and I were sep for about 4 months then she asked me to work on it. But W can't let go of Om. She is still in contact. Tells me they don't have a R and certainly not an A. But they did. I say BS.
Like you I'm in the same place. Not quite sure if I should walk away again or stay and see if it works out. I just feel the longer this is going on the less I can tolerate it. Every time I see evidence again about her contacting him it makes me feel worse. So I blew up about every weekend now on the last 3 weeks. And yesterday I told her I'm considering sep. again. After that she was just being very nice to me but I don't expect any change.
Sorry for the long post and I didn't want to hijack your thread. And unfortunately I can't give you any advice. Haven't figured it out myself yet. Just letting you know you are not alone.