More developments on this in last nights Aust episode:
AUST PACE!!
Ash worked out that Phoebe already knew about the rape. Phoebe realises that Ash now knows about the rape, but doesn't know who the rapist was. She is seemingly just about to tell him it was Mick, when Billie comes along & cuts her off before she says anything. Later on, Billie confirms to Phoebe that Mick, & not VJ, is the baby's father etc. She also asks Phoebe not to tell Ash that it was Mick. When Phoebe asks her about Irene & Leah, Billie says that they can't know either...for the baby's sake (remember that earlier this year Billie confirmed to Phoebe that Mick was her rapist, after she recognised his tattoo. But, when Phoebe asked her if Mick was the baby's father, Billie insisted that it was VJ, so Phoebe dropped it at that time).
So, now we have the situation where VJ & Ash know that Billie was raped & that VJ is not the father, but not who the rapist was (but the spoilers & previews suggest that Ash will continue to try & find out who he is). Phoebe knows that Billie was raped & that Mick is the father. While both Leah & Irene are none the wiser! The plot thickens!