Kevin Federline Says Britney Called Justin Timberlake Night Before Wedding

Britney Spears’ ex Kevin Federline is rewinding to the night before their 2004 “I do” … claiming he got one hell of a shock when he caught her on the phone with her ex, Justin Timberlake.

Chatting with “Entertainment Tonight” about his new memoir, “You Thought You Knew,” Kevin says the late-night call raised serious red flags, and he told Britney he wasn’t down to get married if she was still hung up on her ex … but she brushed it off, saying she was giving Justin a final send-off.

Kevin says he thought it was pretty weird for Britney to be dialing up Justin the night before their wedding … but he took her word for it, figuring she was just closing that chapter of her life.

Kevin admits he was head over heels back then — but when it came to Britney, he couldn’t tell if she was still hung up on JT. One thing he’s certain of … she definitely wasn’t over him.

Britney’s camp is firing back, telling TMZ that with Kevin’s book making headlines, he’s again cashing in on her name — and, conveniently, right after his child support ran out. Her rep adds, “all she cares about are her kids, Sean Preston and Jayden James and their well-being during this sensationalism. She detailed her journey in her memoir.”