A Therapist Is What She Needs
Unfortunately, I don't think there's too much you can do for your friend. It is my understanding that the pain and scars caused by these kinds of events are very difficult to heal. Generally, I think the best way to come to terms with the feelings is to acknowledge them and deal with them (best with a professional therapist).
You Can't Force Her To Get Help
Since your friend wants to just deny her feelings and move on, what CAN you do? You can't force her to feel. You can't force her to get help, unless she's being a real danger to herself or other people. You can't really go to authorities for her, because she would have to present any evidence or accusations herself.
Be Supportive Of Her
The best a friend can do in these circumstances is to be supportive. Keep checking in with your friend about it. Give her room to have the feelings and let her know that you will give her that space, even if she's not getting support anywhere else.
She May Be Distancing Herself From The Pain
Sometimes with very traumatic experiences, a person has to distance herself from the pain. After a time, she may find that her grades are slipping, or she doesn't care about things anymore, or she gains or loses weight, or has trouble sleeping.
Help Her By Suggesting Therapy
If she talks to you about these things, suggest she see her doctor or a therapist. These are the classic signs that the bad things that have happened to her are catching up with her, whether she wants them to or not. As her friend, you can help her keep a watch out for the signs that these bad things are bringing her down.