The You're So Vain star details her life story in Boys in the Trees, and she admits writing about her broken home, which was caused by her mother's affair with a young live-in tennis instructor, briefly brought back the same speech impediment she struggled with when she was eight.

However, Simon, 70, admits putting pen to paper proved to be a form of therapy to help process her feelings about her past.

"I don't think I would have written it until I got to the vast old age of whatever I was when I started it, because you have to accumulate experience and the way you process it and I wanted to find out more," she explains to U.S. talk show host Stephen Colbert. "In fact..., the way of processing information was to write it down, see what it looked like on paper, and see what it brought forth as I was writing it.

"It was very emotional, it was extremely difficult; it took a lot of out me. There were some nights where I just made everybody in my house mad and upset, and I started stammering again. I used to have a very bad stammer when I was a child; I began to stammer again and was very self-conscious of it."

Simon has previously admitted she turned to singing and songwriting to help her conquer the speech difficulty after trying and failing to solve the issue with a psychiatrist as a kid.