he raped his sister because of me

So when my ex bf broke up he punched a hole in the wall of our school he left me but wanted me back a half hour later I said no I thought he'd cool down before the end of the school day but apparently he didn't since I have moved but recently found out because I didn't get back together with him he was so upset that he raped his sister because of me and instead of jail he's in a mental hospital where I live now and when he's out he's going to my school but it probably won't happen for a while but I don't know what to do a little girl was raped because of me I ruined her life and can't reach out to comfort her this is irreversible I knew he had a lot going on and he was mad had I stayed with him until I moved it would have been fine but I didn't I let him fall in love with me and I let myself fall in love with a rapist there was even a promise ring I should have stopped this but I was to blind stupid and self focused to do that and now a little girl has to pay the price what do I do