Kylie thats really horrible news.

Is anything going to come of it? Speaking from experience, as much as it hurts, try to be there for your sister as she will be there for you. I have found the strength to go forward in life and "kick arse" and take no crap from anyone especially male. My sister is older than me, and up until a year or so ago (she's 41) she unconsiously made everyones life **** & pushed family away. She was very moody, selfish, and not a very nice person. She had become bitter and seemed to blame the world and expect the world to owe her.
Everyone has the strength to overcome this. You will never forget but in time learn to deal with it. Ask for help if needed.
You are lucky that your mother has believed you. Or at least acknowledged that something has happened. She will also need u girls as it can't be easy to learn someone you love had such a dark side.
My mother could not accept what happened to her daughters. And even as she was dying she still could not. Perhaps thats the one thing she took to her grave regretting. Knowing what she did and not doing anything about it.
My daughter accused her stepdad of touching her just once inappropriately(thank god not 'down there') and I asked him to leave that night. We had been married ten years. We have since found that it was not true, she just had other issues that she could not deal with, but it makes you open your eyes to the world and be extra wary of people.
Please when you have children watch them carefully and keep 'in tune' so u can be aware if something is not quite right.
Sorry if I sound like a lecture. I just get so mad. It seems to follow you for life. You always seem to know someone that has had something like that happen in some shape or form. Its a horrible nasty world at times with some horrible nasty people.
I really hope that you will be ok. Please don't push your friends away or give up on anything u do. Push forward harder. Make a difference in peoples lives.
Thinking of you and feeling your pain
VONNI