My bonus daughter blames herself... TW

My bonus daughter(12) and son(15) are living with me and my husband. They had been being molested by their step dad and they both said their mom did not know and he threatened them if they tell. They're mom died March 28th from an accidental overdose from pain medication she got from a friend. I'll be honest there are some sketchy things about their moms death but that's for another day. Their step dad said he would bring them here after school ended because we didn't have a vehicle to get to their state. One night step dad was molesting on my bonus daughter and her brother tried to protect her and step dad ended up raping him and my bonus daughter hid in the cabinet to call 911 because he was screaming in pain. My poor bonus son had to get stitches and has been in so much pain making bowel movements. We found out everything and it was heart breaking. My bonus daughter told me it's all her fault her brother got hurt because he was trying to save her. Those two are so close and it breaks my heart she feels guilty. My bonus son has been going through a lot of physical pain and issues. He has had issues wetting himself sometimes during the day and a lot of pain using the bathroom because of his stitches but I know he doesn't blame his sister. He loves her but she was bawling saying it was all her fault and she wished that her step dad had raped her instead of her brother. That is the most heart breaking thing I have EVRR heard! They are on the wait-list for a therapist but oh my God I didn't know what to say besides don't say that.... Does anyone have any experience with sexual assault victims that can plz give me some guidance because that was so heart breaking she would say something like that.