Offer emotional comfort and support. Encourage expression of feelings. Don't ask for details but be willing to listen if the victim wants to talk. If you are not comfortable listening empathically, help the victim find someone who can. Gently encourage getting medical attention, seeking counseling, and making a report, even if the assault occurred some time ago.
Rape is never the victim's fault.
Nothing you did could possibly justify what happened. Films, videotapes and program facilitators are available. Suggested readings Brownmiller, Susan. California Attorney General's Office. Women's Rights Handbook.