Realistic chances of case being dismissed/charges being dropped?

Overview:
Beginning of April, had a fight with my girlfriend. Things happened. I called the police so she would leave. She left. Police came. Detectives wrote down what I said. Asked if I wanted to press charges, I said no. Was given a number and adviced to call Sexual Assault in the morning and talk to a detective. I was under the impression it was some sort of "counseling". Instead, warrants for forceful sodomy and object penetration were taken out against my girlfriend after I was told I needed to give a written statement. Since then she was bonded out. I've called her lawyer, the commonwealth, the magistrate and the detectives and stressed to them that this was not my intent.

Tomorrow is the prelimenary hearing. (See if there is even enough evidence to go forward. - All they have is my statement, no witnesses, etc. (other than me)) My girlfriend has never been in trouble with the law before.

Basically it's up to the judge since my commonwealth attorney has a "no drop policy."

I was told by the magistrate's clerk that the judge presiding over this case usually dismisses cases in which the victims want to drop charges.

What are the chances of this case even going to trial with no evidence, and with me wanting to drop charges I never intended to take out?

Preliminary hearings are mostly ceremonial as the magistrate,prosecuting attorney, and your attorney all make money. Very few cases are thrown out only because of the financial gains of all involved. Welcome to the innocent until proven guilty process. Sorry, but it is only a myth!!

This wouldn't make her "unavailable" for purposes of introducing prior statement. To be considered "unavailable" the witness practically has to be dead or missing at sea for 5 years. Furthermore, this is a criminal case, there's a fundamental right for the witness to face and question their accuser, the "accuser" being the original poster.
Also, there was no chance for the defense to cross the witness when she gave her last statement. There's no way a judge will let it in by itself.

Depends on your state, in California the District Attorney can pick up a case and proceed whether or not the victim goes forth with charges depending on the details of the case. The details in yours don't sound too promising for your girlfriend. Thats basically rape. You can't assume the judge will make a blanket decision, hopefully he reviews them case by case. All you can do is show up and tell the truth.

The only question before the court will be whether the evidence is sufficient to warrant a trial. The judge does not have the authority to dismiss a case that is brought by the prosecutor and supported by the evidence simply because a witness wants it dismissed. If you refuse to testify, then the judge has some discretion. The judge can decide, for example, whether to put you in jail until you agree to testify, or to grant a continuance or to just go forward. However, if you refuse to testify, that makes you "unavailable" as a witness and your prior statements to cops will probably be admitted and will probably be enough evidence. Talk to the prosecutor assigned to the case. That is the only person with authority to decide not to go forward.