“Tristan attended the birthday party with some friends,” a source tells PEOPLE. “Khloé seemed a bit nervous about having him there, but there was never a question if he would be invited.”
“It’s super important to Khloé that True spends as much time with Tristan as possible. Khloé wants True to have a great relationship with Tristan,” the source adds.
Although Kardashian may have been nervous about inviting her ex to attend Sunday’s celebration — especially given her family’s anger over the betrayal — the lavish bash was a success.
“Everything went smoothly,” the source says, adding that “Khloé had asked her family to behave and leave Tristan alone.”
While Thompson, 28, made a brief appearance on Kardashian’s Instagram Story as the pair took some photos with the birthday girl, the source said that was pretty much the extent of their contact with each other.
“Khloé and Tristan posed for some pictures together with True, but otherwise had very little interaction,” the source says. “Khloé let Tristan spend some alone time with True.”
In a super sweet video posted on his own Instagram account, the NBA player held his baby girl in his arms, telling her she deserves “all the jewels.”
“❤️❤️my princess❤️❤️ I love you soo much,” he captioned the clip.
The outdoor celebration was filled with butterfly decorations, cotton-candy vendors, a dreamy dessert table, toddler-friendly play equipment and “unicorns” with colorful horns and pink manes that younger guests could ride around the event.
“Khloé was very excited how the party turned out,” the source says. “It was all over the top and insane of course. But It was very important to Khloé to have this party. True is her life and she just wanted the most special day with her girl.”
The party was attended by Kylie Jenner, Kim Kardashian West, Kourtney Kardashian and Khadijah Haqq. (Khloé’s sister Kendall Jenner was spotted at the Coachella Music and Arts Festival in Indio, California.)
Khloé recently told PEOPLE she’s in disbelief that her baby is about to hit the one-year mark.
“It’s so corny but you don’t realize how fast time goes by until you see a child growing in front of you,” she said. “It’s scary and sad because it goes so fast. Can we slow down time?”
But the reality star has never been happier than she is with her daughter: “I am so utterly obsessed with her. This first year has been amazing. And I really feel like I was meant to do this.”