What exactly have I gotten myself into?

Where do I start I'm 27 married to a 55 yo. We have one DD age 3 together and he has 5 other daughter's from previous relationships, ages 37, 24, 23, 10, and 8. When we first started dating he had custody of his then 3 year old (8 now). Her mom is a list cause and rarely sees or talks to the child. So pretty much from early on I took on the role as mom, she even asked is she could call me mom soon after. Not even a year later and we found out we were expecting our daughter, my first child. Not soon after my child was born, she started to exhibit normal behaviors for a child getting used to a new baby sibling. She was still seeing her maternal grandmother every weekend, and her mother's family had become very fond of me. My husband was working very long hours so I was now her custodial parent, doing everything from sun up to down as her mother. Doctors Appts, School programs, Dance rehersals, you name it. So it was natural for me to also believe that I should be the one disciplining her. Well when she was 6 she left the school and walked with her friends to the candy store without the knowledge of the school, I recieved the call letting me know they were discovered by a teacher trying to sneak back on campus. That evening I have her a spanking, after carefully consideration with her father. That weekend she went to her maternal grandmother and told her I beat her and that she was terrified of me. The grandmother called my husband insisting that he get rid of me or she would open up a can of worms. That she did, Cps immediately took the little girl from her grandmother and placed her in foster care while things were investigated. 2 months later they took my daughter from us, age 2 at the time, on the suspicion that she was also in danger. Come to find out the 6 year old has told Cps I always beat her with belts and alcohol, that I was a monster basically. Well 6 months later I had my daughter back in my home, but since Cps investigating all the siblings his 10 year old was taken from her bio-mom in the process, 6 more months pass and the 10 year old is now home with us. We are still fighting in court to get the now 8 year old back. But the 10 Year old told me her sister told her the whole reason webby w are on this mess is because she LIED. guys I've been dragged through the mud because of this family traumatized and now she's finally coming clean because she wants to come home. But that's not it, the 10 year old has told me since recently finding out I'm pregnant with my 2nd that she will wrap my baby in blankets and throw or in the trash, or that she will suffocate my baby then laugh and says just kidding. I'm honestly considering divorce, not because my husband but because of his damaged daughters and I don't want my 3yo or new baby to pick up there behaviors. Also his 24 yo lives with us she is Autistic. She has been living in the street because she won't stay anywhere where she had responsibility. She has climbed out windows or left the doors unlock and now her behavior is jeopardizing or cps case if we get another referral because of her reckless behavior they can take my kids again,I'm stressed to the max any advice?