Hmmm
I can speak as someone who has been abused by their stepfather and also about what my mother did in response when I finally told her about my abuse.
She was in denial,asked me had I dreamt it all up,had I got him confused with someone else? etc etc.She confronted him and he admitted the abuse,but she still couldn't cope with the truth (especially as he said he wouln't ever do it again and that he was truly very sorry).
My stepfather groomed me (and my mother-there was underlining emotional abuse from him).He told me did it because he 'loved' me too much but also said,that if I told anyone,everyone would blame me and disown me-so I tried to make him happy and to the outside world we looked like a happy family unit.
After I told my mother,they (him and her) gave me the choice of going to the police station-I was 11,and petrified so refused that option,really my mother should of marched me there (but then she didn't 100% believe me or want to believe me-how could her wonderful partner abuse her child?!).This actually fucked my head up more as it was brushed under the carpet totally and there was exceptance of his abuse.
I finally brought charges against my stepfather in my early twenties.,but the damage was done really,I could no longer trust my mother,because she couldn't support me when I most needed it.He was important than her own child.
I would go to your GP,explain and get yourself some counselling as well as your daughter-don't let his abuse ruin the relationship that you have with your daughter,I hope your daughter can continue the strength that she is showing now and press forward with those charges (I wish I had at a earlier age).Support her 100% and tell her,no matter what the outcome of this awful situation,you will love and listen and always be there for her.
He is not the important one,your daughter is.