One great thing I found through my experiences...is that I forced my mind to accept that our relationship was over. I was still friendly and engaging, but in my mind our relationship was done. It helped my cope better with the muddiness of it all. Even if you don't set the boundary with her about getting counseling, etc....you can operate in the mindset that it is over until she starts those things.
Example being that my wife would confide in me and then flirt a little bit. Because I had my mindset in place I didn't take it as "She is coming out of the fog"...I took it purely as she was being nice, but our relationship is still over. I kept this mindset as much as possible until she finally said that she wanted to work on rebuilding our marriage.
As Jack has said before, be very weary of your words, delivery, everything when you deliver your boundaries. In your case...your wife is used to be controlled by others. She could go a couple ways....she could blow up with resentment or worse, she could comply out of fear and not really follow the boundaries with her heart. More just satisfying the controller instead of seeing the opportunity for self improvement.
