I Refuse to Sleep Under the Same Roof as My Stepson — My Daughter’s Safety Comes First

I live with my husband, daughter, and stepson. After we married, my daughter grew quiet and distant. She said it was nothing, but something felt off. One night, just before bedtime, I was shocked to overhear my stepson in her room saying, “I’ll take whatever I want, like always. You’re not going anywhere, and you won’t get it back.”
I was frozen. I couldn’t believe what I was hearing. It turned out he had been constantly mocking and belittling her for months.
I wanted to kick him out immediately, but my husband stepped in and said, “You can’t just do that.” I looked at him, furious. “If you’re not going to protect our daughter, I will. I’ll leave, and I’m taking her with me.”
That night, my husband finally confronted his son. My daughter looked relieved, but I still feel uneasy. I don’t know if this will really stop him. If anyone has dealt with a stepsibling constantly putting their kid down like this, how did you actually make it stop?