Wow. It sounds like you have made a lot of progress and that she is seeing the progress. Kudos. I think you should keep up the good work and give yourself a new time line. (I wouldn't share it with her) I would expect that she is having a difficult time ending the relationship with the OM. While I understand and agree with giving the ultimatum of not allowing a relationship with the OM, I think you may be able to continue to work on yourself and not obsess about it. Maybe she is wanting to find out if your changes will be permanent. It appears, she is using the OM as a life preserver if things don't work out. Her moving back in with you has to be a huge sign to the OM that things are going downhill between them. I am sure the OM is doing everything he can to try and stop it. Don't let him let you fail.
Either way, working on yourself will pay off in the long run either with your spouse or without her. You have done a lot of hard work. Keep it up!
If it took a look time to get into this situation, giving it a few more months is probably reasonable.
Keep going to counseling - it opens up the communication.
