you really left out a lot of info in this post... do you want to date men? do you want to have sexual relationships with them?
assuming the answer to both is "yes", i would recommend seeking out a psychiatrist who specializes in OCD, these intrusive thoughts sound like some of the symptoms of it. a psychiatrist should be able to guide you in treatment methodologies to make these intrusive thoughts less frequent and more manageable, hopefully to the point it doesn't interfere with your life anymore