"The acronym for I Am Not A Lawyer sounds like it should be an Apple buttsex machine."
That is the funniest line I have ever read on this site!
I am a lawyer, in Georgia, so take this for what it's worth. Whether they charge you or not is independent of what they do to her. However, you can bet that her defense in court will be that you were raging on her and she was just defending herself, and she will throw the drugs at you as proof. Now the drugs are in front of the prosecutor and the judge. The odds of you being charged go up (if you haven't been already).
How badly do you want to go through with the prosecution? It may be worthwhile to ask the prosecutor to drop the charges. However, be aware that while you are the victim, you don't have the authority to drop the charges yourself. The state (or I guess it's the "Commonwealth" up there) has the authority to prosecute her even if you don't want the charges to go forward because it is an offense against the state law (that's why the case will be called the Commonwealth v. "THE BITCH").
However, since this is not a case of a man beating on a woman, if you want the charges dropped and she has a half decent lawyer, you may be able to make it go away without a trial and without the drugs being brought into the courtroom as evidence.
Now as to the fact that the cops took the drugs, since it was your house, there is a presumption that the drugs were yours. Unless she can squat double her body weight and looks like it, or you have a jacked roommate, you are screwed. Hold your breath, live right, and hope they don't press charges.
If you are charged, and if you don't have any priors, most states have a first offender program where you do probation, drug counseling, etc, and jump through a bunch of hoops, and get off without a conviction. If you have priors, well, I don't know what to tell you. Either way, unless you qualify as indigent, you will pay a few to as much as several thousand for a lawyer to work you a deal. So you are still screwed, but in a gentler way. Like by Hugh Grant instead of Ron Jeremy. Or so I have heard. Not speaking from personal experience.
Let us know what happens.