I have found that crying can be a good thing!
You are reacting to a situation that it terrible and your body needs a release. Infact I would probably be screaming by now if I was going through what you are.
You have done the right thing time and time again, sweetheart and that takes guts galore. YOu have taken a stand for your daughter and let her now that what ever life may through at her, however bad she feels you her mum will protect her, stand in front of her and stand up to anyone to protect her. That is a fanstastic wonderful thing.
There is just one thing that I want to say, I don´t know if it has been said up screen but remember you are feeling so many different emotions at this time that pretty much anything goes to help you process them, cry, scream, hit a pillow (if you can do this on your own it may be better for your DD) lose the plot if you need to. Remember you are not only going through hell becuase of what has happened to DD; but because of what has happened to your self, and whilst I hate to type this you may in some way feel slightly responisble for what has happend to DD. THE ONLY PERSON RESPONISBLE FOR WHAT HAPPENED TO YOU; YOUR SISTER AND YOUR DD IS YOUR DAD, PLEASE DONT FORGET THAT, none of you (you, your sister, dd) have done anything wrong or to desever this to happen to you, you are an amazing mum and your DD is lucky to have you.
Also remember that your mind may have blanked a lot of what was done to you as a coping mechanism, the termoil you are now in may mean that your mind block is starting to fail, may be not in terms of actual things that happened but in terms of the emotions you felt. Please do considering asking for counciling, also remember that no matter what the time of day or night there are people that will listen both here publically on the forum by private pm and on the phone.
YOu are doing so well, your strenght and courage are fanastic. Please have a hug from me for you and your wonderful brave dd