If I understand "sex aslt by cstdn sex batt vict over 12 und 18 yoa", that means the person had some sort of custodial relationship, such as a police officer, jailer, probation officer, etc., and took advantage of the power of that position to coerce you into having sex. If I understand that correctly, then this is a first degree felony in the state of Florida, with a maximum penalty of 30 years in prison.
In Florida, for sentencing purposes, felonies are divided into 10 levels of severity. A 794.011 (4), which is what I think this is, is a level 9 out of 10. About the only way to make it any worse would have been if he had forced you to have sex at gunpoint. When they calculate his sentence, that racks up 92 points...times 14, or 1288 points. To say that is a lot is an understatement.
To find the recommended sentence, subtract 28 points from the total (1288 - 28 = 1260), and decrease the remainder by 25% (25% of 1260 is 322, 1260 - 322 = 938). That number, 938, is the recommended sentence in months. 938 months is over 78 years.
It is possible to order the sentences to be served consecutively, for example, 14 sentences of 5 years and 7 months, back to back to back to back. Or, if the total points exceed 363, it is possible to just be done with the thing and sentence the offender to life, even though the maximum penalty for one charge is 30 years.
If you're starting to understand that this guy won't be getting out anytime soon, you're getting the picture.
Now, what will probably happen is that they will hang the possibility of a life sentence over this guy's head, and offer to dismiss all but 3 or 4 of the counts if he will plead guilty to what is left, and accept a sentence of 20 years or so for those counts. There is some interplay between you, the prosecutor, the defendant's attorney, and the defendant. If the prosecutor thinks the case is weak, or is afraid that you won't testify or that you will be a poor witness, he may offer a better deal to the defendant. If the defendant is very stubborn and thinks he can win at a trial, he may hold out for a better deal than the one the prosecutor is offering. So, you see, you hold some of the cards in your hand. If you are adamant about testifying against him in order to put him away, that strengthens the prosecutor's hand.
If there is a trial and you testify, you will simply be asked questions about what happened, both by the prosecutor and by the defense attorney. They will be simple questions that you already know the answers to, like, "Is [his name] here in court today?" "Can you point to him?" "When did you first meet him?" "On April 14, 2013, did you come home from a softball game at about 7 pm?" "Was the defendant inside your home when you got there?" etc. The prosecutor will try to show that he did everything he was accused of, and the defense attorney will try to show that you really don't remember what happened very well, or that your version of the story is a little outlandish ("So, you mean to tell the Court that your 9 year old friend was watching, and that he [what he did] in full view of this 9 year old?" "Would it be more likely for him to get caught if he did it in front of witnesses than if there were no witnesses?", etc.) Essentially, you'll just be telling the same story that you already told to police, and you'll be coached on what to say and what traps the defense attorney might set for you.
Usually, if he is convicted, you can make a statement about how his crime has harmed you when he is sentenced. You don't decide the sentence, the court does. And the court can decide on whether to take your victim statement into account, and how much weight to give it.
But from what you've written here, I would guess that the most likely outcome will be that he pleads guilty and accepts a deal to send him to prison for a long time, in order to avoid being found guilty at a trial and being sent to prison for an even longer time.