I'm glad you survived. It's not your fault. Sexual abuse takes away the victim's power and control. Afterwards, the survivor should be allowed to be in control and to make her own decisions. Even if you don't like the decisions she makes, and even if they're not the choices you would have made, you can best support her healing by supporting her decisions and choices concerning how best to proceed.
Many survivors blame themselves for the abuse.
Tell her over and over again that no matter what she did, it was not her fault. No one asks or deserves to be raped. If she feels guilty for not fighting back, tell her that no matter what she did when she was raped, she acted in the best manner she could. Fear often paralyzes people. Submission does not equal consent.