The former football player turned "Today" show correspondent released a statement confirming the breakup after Page Six reported on it Tuesday.
"After 11 years of marriage, Ginny and I have decided to separate," Barber said. "This decision was a painful one, but we are moving forward amicably and will continue to work together to raise our children with the love and dedication they have always known."
According to the Post's report, Barber left wife Ginny, who is eight months pregnant with twins, for former NBC intern Traci Lynn Johnson.
Ginny reportedly found out about the relationship last year, when Barber moved out of the couple's home on New York's Upper East Side.
Johnson was photographed sitting next to Barber at the Washington screening of a documentary on Senegal that he hosted for the Travel Channel.
"We were shocked to find out that he could walk out on his wife of 11 years while she's pregnant with twins," a Barber family friend told the Post. He was with this girl in Senegal while Ginny was three months pregnant. And we believe she was also with him in Vancouver while he was blogging about the Winter Olympics for Yahoo.com."
Barber declined to comment to the Post about the infidelity allegations. Ginny, a former fashion publicist and full-time mom to the couple's two sons, also declined to comment.
Barber spoke about his parents' breakup in a 2004 interview with the Post, and called out his father for his infidelity.
"I don't give a [bleep] that the relationship didn't work," he said in the interview. "Not only did he abandon her, I felt like he abandoned us for a lot of our lives. I have a hard time forgiving that."