Dwayne Wade and Gabrielle Union (open in new tab) have a great relationship, but that doesn't mean they haven't gone through some tough times.

In the ESPN documentary D. Wade: This former NBA star shares an episode that he says was the hardest moment of his life: it was telling his now wife that he had a child with another woman.

Wade and Union first began dating (open in new tab) in 2008, but they broke up in 2013. During that time, Wade had a son, Xavier, now 6, with another woman; when he reconciled with Union, whom he married in 2014, Wade had trouble breaking the news to her.

In the documentary, Wade recounts his experience (opens in new tab):

"I had a child with another man and I had to tell her. The hardest thing I ever had to do was to have to tell Gabrielle Union, as a man, that I had a child with someone else. I couldn't sleep. I couldn't even eat."

"When you're holding onto something that you know is going to come out and you have that information and you know it's going to mess up somebody's life, somebody you care about, somebody you love, if it doesn't hurt you, you're not human ....... Me and Gabe went through something we never wanted to go through.

Wade's children (he is the father of 18-year-old Ziah (opens in new tab) and 12-year-old Zaya (opens in new tab) and the guardian of his nephew Davion, 18) have always played a major role in his life and relationships. When he proposed to Union in 2013, his children even helped him pop the question.

"She's not only marrying me, she's marrying all this baggage," he says.

Wade and Union now have a one-year-old daughter, Kaavia (opens in new tab), whom they welcomed via surrogate. Kaavia's birth prompted Wade to retire from professional basketball in 2019.

D. Wade: The show will premiere on ESPN on Sunday, February 23 at 9 p.m. ET.