What should i say to my ex best friends email that she sent me barely apologizing for what happened between us?

Well we were sooper best friends for a while and she lived in a really bad place. My parents decided that she could move in with us since we trusted her so much and she was like a sister to me. I did everything for her. She never really did anything in return during our friendship.

She moved back into her old abusive home because she just wanted to be closer to her boyfriend. She lived downtown and so did her boyfriend but I didn’t. I know that’s the only reason why she moved back because she absolutely hated her dad more than anything but she went back without telling me anything.

The day she left was the last day I spoke to her and she sent me and email a couple of days ago and I don’t know what to say. she barely apologized in the email. I don’t really know what else to say to explain much but if you want more information just let me know, thanks.