Answer
Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
As for your question, you have taken the right decision by leaving this environment. You do not need to apologize to your stepfather who has abused you instead of protecting you.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
You owe no apology to your stepfather who raped you and forced you to leave home.
You did the right thing to leave such an abusive environment. He betrayed the trust and instead of protecting you, he abused and victimized you.
So, never feel guilty about your actions to protect yourself. If you do so, you are empowering the abuser and telling them it was your entire fault.
Certainly it was not your fault. It was the case of a rapist and an innocent victim who could not defend herself except by leaving home.
Allah Almighty knows best.