LD: I can understand how his going back on his word affected you. Whether or not people agree with you that it is rape really doesn't matter. The fact is: You asked him to stop this behavior and he agreed to it, and then he broke your trust and went ahead and did it anyway.
You can forgive him for this. This is not the end of the road. Read the rest of this board; there are people here who have forgiven things that just boggles the mind. This is not a hopeless situation.
Now, having said that, I want to put a completely different type of thought in your head. Do you see that YOU also broke his trust? That your actions have broken him down into a person who has little sexual confidence, feels hopeless over the fact that his wife doesn't want him, and is emotionally devastated. Do not make the mistake of thinking that the lack of sex in your marriage is no big deal and hasn't taken a toll on him. The toll that it takes is SO HUGE that I couldn't begin to describe it.
So you both have made awful choices, with regards to your sex life. You went to therapy and had a nice week and, from the sound of your post, went right back to rejecting him. I am NOT condoning what he did to you after that, but I can see how he felt that it was all a big act and that your changes were not for real. I have been there with my own husband and I know how that feels.
So, I will leave you with one final question: Are you certain that your husband is awake when he does this? Is he fully aware that he is doing something that you asked him not to? And what did he say about the incident after therapy when he tearfully promised not to do that anymore? ok, so it was more than one question...:D