You will survive and overcome this! Sleep in the immediate aftermath of trauma is actually a healthy and therapeutic response . . . your body is doing what it is programmed to do.
Of course, everyone out here wants the person who did this to you to be held accountable. No blame, though, for not going to the police, but sad that you feel you can't.

Do you think you can start a log to record the events - time, place, details? I ask for a couple of reasons . . . 1) providing an accurate record while details are still fresh so that you have what you need in the event you chose to report the crime at a later date, and 2) processing on paper what has happened to you, even if you don't ever share it with anyone else, would be beneficial to your mind and spirit. This rape will obviously completely dominate your waking thoughts for a while, so why not start jotting everything down? You may find that just the act of putting it down on paper as a conscious choice will be empowering for you. Empowering enough to get up day after day, take one step at time towards recovering, re-engaging in life. Maybe your friend who knows of this can dictate some notes for you before leaving the country if you think that would help? If this happened on campus or at an off-campus school sponsored event, you may want to check into the school's rape policy - just to be informed, nothing more.
Please do seek counseling as soon as possible. The sooner you seek support by those trained for this type of trauma the better you will be.
* rain.org
* RAINN operates the National Sexual Assault Hotline at 1.800.656.HOPE
* Visit online.rainn.org to chat one-on-one with a trained RAINN support specialist, any time 24/7.
Bless you!