Thanks for the reply.
There's nothing much you can do at this point. It would be unwise to talk to the police when you're a suspect. And, of course, you shouldn't talk to her. If she's angry enough to press false charges, she's a loose cannon and you're best off avoiding her.
About the only thing worth doing would be to have some local consultations and find yourself the name of a lawyer. You don't have to retain him/her, since there's nothing that a lawyer can do for you now either. But in the event that the worst case scenario happens and the police want to arrest and charge you, you'll have the phone number of the criminal lawyer you want to use handy, and that lawyer will already know about your situation and can step right in and be quickly up to speed.
I can't tell you what, if anything, will come of this because I know even less about this than you do. But I can tell you that a sexual assault is a serious crime of violence, and the very fact that you're still free to get on with your life and have heard nothing is a very good sign.
If you tell me what US state you allegedly committed this crime in, I can tell you how long it could be before you're completely out of the woods. But with a felony charge, technically, the police can investigate for a long time -- years -- before a case would be too old to be prosecuted . Theoretically, however, since they know the whereabouts of the complainant and of you, there's no real reason for a delay. So the longer this goes on with nothing happening, the better the chance that nothing ever will.