How do i help my friend get over a childhood rape incident?

When she was around 8 her moms boyfriend had raped her...he is currently in jail but any boy she meets she cant handle bcuz it brings bad too many bad memories about her incident and in a couple of years(around 4) he getting let out of jail and my friend is worried he will hurt jer mom and rape her sister and hurt the rest of her family like he promiced.i try to get her to talk fo people about it but that isnt helping.none of her family knows except for her mom and her mom knows very little. I have never been in her position so i dont know what to do can someone please help me by telling me what i can do to help my friend