LISTEN TO AND BELIEVE THE VICTIM.
The most important thing that you can do for the person in your life who was assaulted is to listen to her when she is ready to talk and believe what she says. Be very patient with her, as it will take time for her to sort out her feelings. Reassure her that her feelings are normal responses to a traumatic event and that in sharing those feelings she is taking steps towards working them out.
Communicate to her that she is not to blame for being sexually assaulted. She needs to know that you realize that it was not her fault. Sexual assault can happen to anyone regardless of age, income, appearance, or physical strength. However, she may be blaming herself or having regrets about what she did or didn't do. Your role may be to help her see the event more realistically as well as to let her know that you still care about her.
After going through an experience in which she had no control over what happened, she may feel a general loss of control over her life. One way that she regains control is through making decisions about events that affect her life (e.g., reporting the sexual assault, moving, changing jobs, etc.) Supporting her decisions and resisting your own tendency to "take care of the situation" can help her to regain a sense of her own personal power.
Assuming some of the blame for what happened is common among friends and family members who may feel that it is their responsibility to protect the victim. Remember that there is no one who exists in a protected environment at all times. We are all vulnerable regardless of how much caution we take. The only one to blame is the assailant himself. Try not to overreact by becoming overly protective of her. This will only reinforce her view of herself as powerless.
If you are feeling a need to seek revenge against the person who did this, you are not alone. Anger is a natural reaction to what has happened, but extreme rage toward the assailant may frighten the victim and cause her to worry about your safety. Seeking out a third person to whom you can express your anger may be beneficial to all concerned.
If your relationship with the victim includes being a sexual partner, you may expect some temporary disruption in previous patterns of sexual activity. Reactions vary tremendously depending on the individual and her particular style of recovery. She may feel anxious about how you will respond to her as well as how she will respond to you. Be careful not to put pressure on her but to let her take control of sexual decision making during this time. Try to understand and be sensitive. It will help her to communicate openly about her feelings and thus overcome any difficulties.
When a sexual assault occurs, family and friends of the victim often feel that they have been victimized as well. If you are a friend or family member, you may find that you will experience some of the same reactions that are frequently expressed by the victim. Be aware that you also need support in understanding your own feelings that might seem overwhelming at times. Reach out for help when you need it.