This is what I remember:
It is about two sisters, one maybe about 13, the other one at least 10 years older.
Their parents die in a carcrash so the older one becomes hee younger sister's guardian. At the time the older one is heavily pregnant. Her DH/DP is very self absorbed and constantly needs to be the centre of attention.
The baby is born and for some reason I seem to remember they call her Opal (I might be wrong here!).
In the end the older sister shares a special moment (can't remember if it's just a chat or a kiss or possibly even sex) with DHs friend. I think DH sees them and ends up committing suicide.
I've been trying to google for ages but no luck.