I read it first on a post, then I tried to verify and I found this biography, published by The Cambridge University Press. I couldn't believe it, but I trusted the "authority" of the publisher. So, thank you twice.

You’re so welcome! I’m glad I wasn’t out of line. I don’t want to paint Tchaikovsky as a perfect person, but a lot of what Jackson put in that book is just nonsensical. And like you say it’s too bad because generally that publisher and the music handbook series is quite good