Cynthia, who was married to the late Imagine star for six years until their 1968 divorce, claims Ono deliberately excluded Julian from working on Love because she prefers to think Lennon never loved anyone else before they wed in 1969.
She says: "It seems to me that Julian could have brought something valuable.
"(Ono) is a very powerful woman. She controls a quarter of The Beatles legacy. She can make or break new projects.
"After John died I understood that she was positioning herself as the only woman in John's life, so that she could manipulate history."
Love has been produced by The Beatles producer George Martin and his son Giles, and is the soundtrack to Cirque du Soleil show of the same name. Lennon was shot dead in New York in 1980.