"Djimon Hounsou and Kimora Lee Simmons have officially separated after 5½ years," the actor's rep tells PEOPLE exclusively. "Though never married, they have one child together, Kenzo Lee Hounsou, who is 3½ years old."
"There have been quite a few hurtful rumors circulating. The truth is Djimon + I have been separated for some time," Simmons Tweeted Wednesday. "We have remained happy, loving, co-parenting friends + family. We all have much to be thankful for."
The Amistad star, 48, first met Simmons, 37, now the president and creative director for JustFab, in 2007, following her split from husband Russell Simmons. She later said they were "kind of" engaged.
In 2009, they announced the arrival of their son, their first child together. Simmons also has daughters Ming, 12, and Aoki, 10, with her ex-husband.