Blending a family with a daughter that has trauma

I have been married 3x. My first was to my daughters dad who was abusive. My second husband had a son and my step son ended up SAing my daughter from when she was 4 to 7. He was 14-17 and when we found out my ex's excuse was he was just a boy. My daughter is 13 now and my current husband has been good to us. He understands my daughter's trauma and treats her like his own. He has a son that turned 16 today but he was living full time with mom. Saturday my husband said he had to pick his son up. Things happened with his mom and CPS needed him to get him. It was a shock. I had no time to prepare my daughter. And before we knew it we are a home of 4 now. My daughter has been having panic attacks because she's scared of a repeat and I told her not to worry. It won't happen again but if something happens with anyone to please tell me as soon as possible. I think she also feels like she doesn't have a dad anymore because he's been preoccupied with my step son because he hasn't taken the move well. I might also add my step son has a drug problem in the past. So there's a lot of baggage coming with him. I've tried to be nice and even asked if he wanted to go out for his birthday but he declined and stayed in bed all day. Trying to blend this family with so much baggage and trauma is difficult.