I know what your going through. It is up to your gf, but you could always make an annonomous *sp????* report. It is still illegal, she can still press charges. But it will be harder for him to be put in jail.
My first reation would be to warn the people that have kids that are close to him.
Just support her in anything she does. Watch her moods, and hwo she is. It can depress a person to be sexually molested for their entire lifes. If at all possible try to get her to a physcologist (grrr, bad spelling tonight!)
Neptune, Zion, Enigma,