Yes, I have gone to a certified imago therapist. I will tell you it is the most effective method I have seen. It turned my relationship around, stopped the conflict and really helped us to get back to a positive place and greatly improve our communication.
As I read your post, I remember feeling as you do at one time. I remember feeling frustrated, having all of these hurt feelings that I needed to talk about. In Imago, you will have a chance to heal all of that, but first you have to learn how to communicate those feelings so your spouse can understand them. I am certain that you have aleady tried to tell him before, but he felt insulted or attacked. Bite your tonge today until you learn this skill, try to have an open mind and give it a chance. I will be honest that I haven't dealt with substance abuse in my marriage, but the frustrations and hurts; yes. This mirorring that you speak of is to help you two learn to listen to one another. You must learn to listen first before you get all this off your chest to your spouse. Look at it this way, if your spouse does't feel heard then how is he to listen. I hear in your post that it is difficult to participate and listen without being heard. Imago made it possible for my husband to hear my feelings without feeling attacked. We both are able to listen better and act on fulfilling each others needs. Give it a try and best wishes to you.