Not wanting to have sex?

the thought of sex it self disgusts me. Any time my fiancee brings it up I want to hurl. I completely reject him sexually and cant see him naked with out being sickened. Here is why this bothers me... HE IS HOT. SUPER STAR hot. we used to have sex all the time but now.... and its just not just with him even Orlando Bloom or thoughts half naked men you see out side Calvin Kiln just make my skin crawl (in a bad way) and it even makes me sick to "satisfy myself" oh and this has been going on for almost 5 months. >.< I know this is a medical disease but I dont remember the name of it or treatment. Please if someone can send me a link or the name of it please do! thank you!