However he's now issued an apology to the star - however, he has not explicitly apologised for making the claim, only that he didn't warn Portman she would be in the book.
"As some time has passed I've realized that many of the criticisms levelled at me regarding my inclusion of Natalie in Then It Fell Apart are very valid," he wrote on Instagram.
"I also fully recognize that it was truly inconsiderate of me to not let her know about her inclusion in the book beforehand, and equally inconsiderate for me to not fully respect her reaction.
"I have a lot of admiration for Natalie, for her intelligence, creativity, and animal rights activism, and I hate that I might have caused her and her family distress. I tried to treat everyone I included in Then It Fell Apart with dignity and respect, but nonetheless it was truly inconsiderate for me to not let them know before the book was released.
"So for that I apologise, to Natalie, as well as the other people I wrote about in Then It Fell Apart without telling them beforehand."
He did, however, acknowledge his inappropriate behaviour given how young Portman was at he time, which she characterised as "creepy".
He wrote: "Also I accept that given the dynamic of our almost 14 year age difference I absolutely should've acted more responsibly and respectfully when Natalie and I first met almost 20 years ago."