I think my step sister is a pedophile. Do they change? Trigger warning!

My mom married this horrible man when I was younger and One of his kids came to live with us. She is about 6 years older than I am. She was sexually abused by her moms boyfriend. She has 7 kids now. When I was 5 she started to molest me in the middle of the night and say it was to test me and make sure I’m not allowing men to touch me. She would make me give her my things to “bribe” her not to tell on me. Our parents made her babysit everyone’s kids. If they were babies she would do something sexual to them like pour warm water on their genitals , rub things on them etc. she would do things to simply torture them mentally. I was a terrified child and my parents were abusive and would beat me for anything. So I didn’t tell a soul. Now that I am older I know how horrible she is. it worries me she has kids. she makes it seem like she is an amazing wonderful protective mother on social media so I don’t know if she has changed. Do these type of people change? Last I heard she was in school to become a nurse. I am still working through all my own trauma and it has been to long to report her as I am now 27. She is married to a woman now and they just did artificial insemination to have another baby of their own.