The pop star and actress insists she never cheated on the retired Dallas Cowboys quarterback, but couldn't tell him she wasn't still in contact with the man who called her "sexual napalm" in a Playboy interview.
In her new memoir, "Open Book", Jessica reveals she always told Tony when John contacted her, but things fell apart when he discovered an email from the singer to his girlfriend. "He (Tony) accused me of seeing John behind his back," she explains. "I hadn't cheated on Tony at all, but I could not lie and say I hadn't even seen him (Mayer)."
" 'Nothing happened,' I said," Jessica wrote in her book. "Tony didn't believe that for a second. And within that second, he broke up with me right there. Two years, gone with an email."
"I could trust that Tony would never tell the press that John Mayer caused the breakup. It would imply that he wasn't enough for me. Tony soon realized I was telling the truth. Of course I didn't cheat on him. But our breakup had been so ugly that it shocked me into realizing it had been necessary."