While I am not asexual, I can relate. I feel very uncomfortable about my body. Just the thought of someone seeing me naked or that evil part really kills me, but I can't say I don't desire men even if I haven't gotten the nerve to be intimate yet.
I had an asexual before and he never really "came out". To be honest, it's not something that people usually come out with, at least in my experience. Most people share it without the typical coming out fears. Usually people are just honest and open about not being into sex. It's different in some ways, but people don't treat it as a major thing like coming out as gay or trans. Then again, I could be wrong on this, so take what I say with a grain of salt.