Hey wife, this rape that your husband went through sounds very similar to my experience. And yes I would very much call it a rape. I had buried this event for 20 years of my life and only after an extremely emotional event in my life (mother dying) did my memories of it start to boil to the surface. The memories did not come out all at once, just vague memories to begin with but after working very hard to figure out what had happened they are now full blown in my face all the time.
I've had similar feelings that your husband has had, shame, guilt, feelings of less than a man. One of the worst feelings I have had is why would I feel so awful about this when as you said "this is supposed to be a guys dream". It is not a guys dream to be assaulted, to have his consent callously disregarded. I was not in a relationship at the time so the feelings of guilt that I have are not from any thought's of cheating.
Any advice I have would be to take your husband seriously. In the face of an assault people can react differently, whether a 200 lb man or 100 lb women. The shock of the assault could have made him react in many ways but it sounds like your husbands reactions was to take his mind out of the situation, like I did, but of course that left his body helpless. If his problems are similar to mine he will need your support and a therapist as well. Stand by him and take him seriously, what he says makes very much sense to me. It does happen.
You might want to research the subject of female on male rape, there's lots of good info out there and it will probably put your mind more at ease when you do.
Good luck, I hope you can come to terms with things