I've had this. It happened twice, just after the birth of my children. I would fancy other men, even lust after them, but I didn't want anything to do with dh. I used to compare him unfavourably with other men - why were his legs so white and skinny? etc. Mine has really bad psorasis too and that didn't help, I would feel disgusted by him at times. I felt tremendously guilty about all of this and even spoke to him about splitting up. I loved him as you have said, as a friend, a brother even, but not as a lover.
However gradually things changed. I think he knew how I was feeling and so he began to make a bit more of an effort. He was kind to me, he supported me, and eventually I began to see these positives over the negatives.
It is true that you have to start from scratch. Remind yourself of why you are with him, what attracted you to him? Then discover if that same person is still there, because if he is then you can be attracted to him again. Try to get a couple of evenings out just as a couple. Do nice things for him, if you act in a nice way towards someone, not only will that niceness be repayed but you will find yourself liking that person. It really does work. If you can't go out, get a funny DVD and a bottle of wine. Read books together and review them to each other. Listen to music together. The idea is to do stuff together, so that you can relate to each other, find out about each other again.
It will come back, you just have to be patient and work on it. Be honest with him too, he has to help you out here, it's not just your problem.