Alexandra Pettifer said journalist Martin Bashir's false claim that she had an affair with Prince Charles severely affected her personal life.
The BBC director general made his latest remarks following the Dyson report and Prince William's comments that the interview "should never be aired again."
The former BBC broadcaster insisted his scheming didn't do anything to harm the princess.
Lord Tony Hall helped cover up the unethical way in which reporter Martin Bashir obtained an interview with the late royal, an investigation found.
An investigation into how the journalist secured a shocking interview with the royal concluded that he acted unethically, and that the BBC helped cover it up.
Bashir has been accused of forging documents in order to manipulate Diana into sitting down with him in 1995.
Diana's brother says interviewer Martin Bashir used lies and forged documents to convince his sister to speak out as her marriage to Prince Charles crumbled.
The 57-year-old former "Nightline" and MSNBC host is now the BBC's religion editor.