Tristan Thompson and Khloe Kardashian have had a tumultuous relationship over several years. Despite this, the Cleveland Cavaliers center and the reality TV star have come together on special occasions in the lives of their children.One such reunion happened on Monday when their son Tatum celebrated his third birthday. In an Instagram story, Kardashian shared a clip from the Disney-themed birthday celebration.Khloe Kardashian posts an Instagram story showing Tristan Thompson in attendance for their son's birthday party. Credit: Kardashian/IGIn the IG story, Thompson and Kardashian lead the party's attendees in singing "Happy Birthday" to Tatum. Also featured in the clip are mascots of Disney characters, such as Mickey Mouse and Donald Duck.This birthday bash brings together two individuals whose past relationship took many twists and turns. Thompson and Kardashian were first linked in 2016, and in December 2017, the couple announced that they were expecting their first child.However, just as their daughter True was born in April 2018, controversy ensued as Thompson — who was about to go on his fourth trip to the playoffs with the Cavaliers — was seen being intimate with another woman in videos posted by TMZ.A year later, the couple split after Kardashian found out that Thompson had allegedly been seeing her best friend Jordyn Woods. Thompson and Kardashian would have an on-again, off-again relationship over the next three years, a span of time highlighted by the birth of their second child, Tatum, via surrogacy.At present, the two exes appear to be single. From time to time, they reunite at gatherings like their children's birthday parties, as seen in Kardashian's IG clip."I think I handled it the best that I knew how": Khloe Kardashian opens up on "traumatic" Tristan Thompson situation before arrival of their first childIn an episode of her "Khloe in Wonderland" podcast earlier this month, Kardashian recalled how she dealt with the news that Thompson had allegedly cheated on her around the time of True's birth in 2018."Obviously, no one can prepare you for something like that," Kardashian said on the podcast. "I was nine months pregnant, I was having a baby two days later, and it was so public and it was everywhere. But I think I handled it the best that I knew how."Kardashian added that she learned how to cope with the Thompson situation by drawing on her experiences of going through her divorce from two-time NBA champion Lamar Odom.