A month ago, when PEOPLE published an exclusive excerpt from tennis star John McEnroe's new memoir, "You Cannot Be Serious," he told the magazine that he had yet to hear from ex-wife Tatum O'Neal, whose portrayal in the book was less than flattering. McEnroe, 43, has now heard from her. O'Neal, 38, says in an interview to air on ABC's "20/20" this Friday that McEnroe took steroids while he was on the pro tennis tour and used cocaine and marijuana -- though not when he was playing. Highlights of the interview have been obtained by Reuters. Asked whether sports officials knew about McEnroe's alleged steroid use, O'Neal told interviewer Barbara Walters: "I never read about it. I made him stop because he was becoming violent." The "Paper Moon" Oscar winner discusses her own drug use in the Q&A, telling Walters that she is "being drug-tested by a doctor in L.A.," and adding, "I've been clean now for a few months." McEnroe and O'Neal divorced in 1992, after six years of marriage. Their three children live with McEnroe and his second wife, singer Patty Smyth, 44. Reuters reports that in a statement regarding O'Neal's remarks to Walters, which he issued through his agent, McEnroe said, "I am very disappointed in Tatum's statements. I had hoped that after all these years she would see things more accurately and that she would share my concern for the welfare of our children."