How can you tell if a woman is a transvestite?

My best friend had a girlfriend who was very attractive ,slender and feminine ,very girl like.After they had sex though she told him she used to be a man.However she had her adam's apple removed , and obviously removed her penis.My bud told me this yesterday and hes stoned hard I couldnt believe it I mean his body had curves like a female and everything .He told me because Im his bro but I dont think he told anyone else.Shits nasty to me.Anyways I talked to a female whom i didnt know was a trans in the apple store in soho she seemed like a female so I started a simple convo but she told me she was a he before I could advance any further .I was digusted and left the store but glad She was honest before things would escalate.I guess some things were obvious to me like big hands and big feet but some girls have these features regardless due to genes .I know that even if he has a vagina I dont know what I do if I had sex with a dude or a girl who used to be a dude .Ever seen Hangover 2?