...... worrying about your boyfriend, right now. You are NOT responsible for his well-being, so leave this fellow out of the discussion, at the present. You've been traumatized and you do NOT need to burden yourself with additional and unwarranted shame where his responsibilities or consequences are concerned. This is about you, not him.
I would strongly urge you to consider the following options, in order, as possible courses to take:
1. call the local rape hotline for more trained and specific help
2. tell your mom
3. file criminal charges
There is a strong concern about your boyfriend that I have, as a mother and as someone who was once 13. This individual is way older than you and this relationship could be very unhealthy for both of you. You have the rest of your life to find a committed partner and learn how to cultivate a safe, loving, and healthy relationship. There's no need to rush into growing up - honestly, I type this from personal experience. Sure, you may want to inform him, but right now is all about you, your recovery, and moving into some healing.