I think you need to be fully emotionally detached regardless of whether you interact with him or not. I think any interaction you have should be light, impersonal and positive. Any negative interaction only pushes him away. I don't think you should ever look like you are going out of your way to see him... or avoid him. And when you come in contact you should smile, wish him well, and leave positive memories. Fun, impersonal and positive.
If he asks personal questions just say positive things, life is good!!! Be vague about your personal life and look awesome. Do not ask him any personal quesitons. Don't tell him you want to get back together or go to counseling (that's enough to make any MLCer run the opposite direction!!!). Just look like you are moving on with your life and that you are happy with it. And you be a friend and wish him well. Don't show any jealousy, anger or anything (no matter what he says!!!). Tell him you are happy he's happy and tell him you support him in finding his happiness wherever it be (and support him no matter how crazy, painful or stupid his words are).
If he feels supported by you he will have a more difficult time hating you. It's harder to divorce someone you don't hate. It's harder to leave someone who supports you and is a friend.
This would be my advice as well, for what it's worth. If your husband is getting some of his emotional needs (like friendship) met by you, and other emotional and physical needs met by OW, then he will continue to cake-eat and not have to make any choices. I agree with your counselor.
