At least 14 of the 25 original members of the thinktank quit after a report that Sir Owen Glenn was accused of physically abusing a young woman in Hawaii in 2002.
He entered a plea of "no contest", neither admitting nor contesting the charge, and later said there was "no truth to the allegation".
There was also concern at the use of personal equipment, such as laptops and phones to record sensitive information.
The charity was dealt another blow when Internal Affairs investigated allegations payments were made from the Glenn charitable trust to a bloodstock company and to the multimillionaire's personal account. That investigation is ongoing.
Rei said the controversy had slowed progress to an extent but the focus had always been one of quality research rather than speed.
She said Sir Owen spoke to the United Nations Human Rights Council in Geneva in November and had invested more money on top of the $2 million he had already given to the inquiry.
"He wants this done and he wants this done properly. He has donated a further $1m but if I went to him and said we needed more to get this done I know he would give more."
Rei said family violence needed the same long-term approach as campaigns used to reduce tobacco use and lower the road toll.