I don't know if this is relevant or helpful but for what it's worth:
A good friend of mine committed suicide when I was 18. There was a big group of us all interlinked by siblings/friends/boyfriends etc in a small, very close knit community. I was also very good friends with his girlfriend.
It absolutely rocked us all, we still all think about it many, many years later and it has really changed our perspectives on many things.
What was probably unknown to parents etc was how much we needed each other. We didn't want adults talking, we wanted our stories and memories etc. What was also extremely unhelpful was the number of comments we heard in passing about how 'the girlfriend' was to blame (this was from adults who were unconnected but honestly, we're talking openly in the local shop). I am sure some of this filtered back to his girlfriend (who was obviously in no way to blame).
Don't forget the stigma that she will feel is attached to her now, for many, many reasons, that is absolutely devastating for a young girl to deal with on top of everything else.
Cut her lots of slack, tell her siblings to leave her alone, be there for her, never judge, let her talk, get counselling but on her timetable (this may be in a years time), and just live and cherish her every single day.
You are doing a great job I'm sure. Keep it up. Your little girl is still in there.