Detachment can be a good thing. It's something I've had to do in my marriage to avoid getting caught in unhealthy emotional patterns.
Regarding couples therapy. Like your husband, my husband did not want to go. But because he is so passive aggressive, he "agreed" to go and then was not cooperative. After a few months of this, the therapist sees the dynamic and gives me some very good advice: don't expect more from the marriage than you get, don't give more than you are getting, he isn't going to change, set your boundaries, cultivate lots of outside interests and friends.
This worked well, but what didn't go well was that not only did my husband refuse to use some of the methods we learned, but his behavior got worse. He became even more passive aggressive, manipulative, neglectful.
So I guess it's my long way of saying, it will definitely help you to go to therapy but it may not be productive to drag him along if he doesn't want to go.
You sound like a very intelligent, insightful person. I'm sure whatever road you take, you will be successful! Good luck.