Cross-dressing, Trapping

Perhaps this isn't exactly the right crowd to propose this question to, but then again, no other crowd seems quite right. For the past two and a half years I've been dating the same crossdresser. She's awesome and we're thinking about making it permanent, it would be just like a commitment ceremony, but here's the thing: I haven't told my parents about her yet. For two and a half years I've been talking about my girlfriend but they've only seen her a couple of times and it took gobs of time on both our parts to work up the courage to even do that. She's passable enough that it worked those two or three times but they think she's a girl, albeit a bit of a manish-looking one with a bit of a deep voice... They are hardly tolerant of gays at all and would rather see people like me not exist, although of course they don't exactly know they hate me too. The question is, how do I come out to my parents this late in the game? I love 'em to pieces, just really not their religious traits which are making them act like assholes whenever the subject comes up. If they don't like gays they'll double-hate me for lying to them and I would legitimately fear for my girlfriend's safety if she went over to their house to meet their friends. It's killing the both of us since both of us want to tell them but neither of us can think of a way that won't mean that I never talk to either one of them ever again.

:( Advice at all?