after reading your intial post it seems like you already know what you need to do. stick it out. i think you just needed the confirmation and support, which is what we're all here for
it's a dicey situation only because you know there's more risk involved, but risk is what starting a relationship's all about. anytime you meet someone new you're going to be wondering "dude, what if she's like, a satan worshipper who cuts herself at night?" or "what if she's going to cheat on me" or what else may be wrong with her. you just have the confirmation now that something MAY be up, a disease is definitely something to be scared about.
it's about mutual respect. you have to respect her enough to let her hold her own until she's comfortable enough to let you in, and she has to respect you enough to not screw you over (which she seems to, because she warned you there "may be something down the road" so to speak). wouldn't it be worse if you woke up with an STD she never told you about? happens all the time- just be grateful you're not in THAT position.
i think you're just visibly uncomfortable with the situation and trying to justify a way out of it, feeling she OWES this information to you. she really doesn't, it's none of your business until it impacts you- and so far it hasn't. if you were sleeping with her and it was an STD, yea that quickly becomes your business. an embarassing rash that'll go away in a few weeks? naaah.
stick it out. trust me, it'll be worth it