Cardi B 'Looked Sad' in First Appearance Since Split From Husband Offset, Says Onlooker

One day after announcing that she and husband Offset are not together anymore, Cardi B turned up at E11EVEN in Miami for an appearance as part of the annual Art Basel international art fair.

Rocking a rainbow-colored wig and see-through long-sleeve black minidress with a black strapless bra, the “Bodak Yellow” rapper, 26, walked the red carpet before heading inside the event around 3 a.m. Thursday morning. She was not wearing the $500,000 eight-carat tear-shaped engagement ring she’s consistently had on her finger since the Migos rapper, 26, popped the question back in October 2017.

Though audience members were told Cardi would be performing at the event, an onlooker tells PEOPLE that she instead mouthed the words to a couple of her songs as they played and took pictures.

“She wasn’t singing or anything,” the eventgoer, who also sent PEOPLE exclusive video from the event, said. “You could tell she wasn’t her usual energetic self. It’s like she was trying to put on a good face but she looked sad.”

The video shows Cardi dancing with pals in the spotlight. Cardi also took the mic and asked the DJ to play Bobby Shmurda, a rapper who supported Cardi’s music career early on by reposting her videos.

Early Wednesday, Cardi revealed in an Instagram video that she and Offset were calling it quits after just a year of marriage because they “grew out of love,” adding, “You know I’ve been trying to work things out with my baby father for a hot minute now.”

The couple, who welcomed daughter Kulture Kiari in July, remain cordial, she added.

“We are really good friends, and we are really good business partners — you know he’s always somebody that I run to talk to, and we got a lot of love for each other, but things just haven’t been working out between us for a long time,” the Invasion of Privacy hitmaker added. “It’s nobody fault, I guess we just grew out of love, but we are not together anymore. I don’t know, it might take time to get a divorce, and I’m going to always have a lot of love for him because he is my daughter’s father.”

RELATED: Cardi B and Offset’s Marriage, Baby and Breakup: A Guide to Their Tumultuous Relationship

While representatives for Cardi B and Offset did not immediately respond to PEOPLE’s requests for comment, a source told PEOPLE, “They have obviously had huge problems for a long time.”

“They’re still very close and really do care for one another,” the source added. “Their priority now is their daughter, and they plan to be solid co-parents.”

RELATED VIDEO: Cardi B Says She and Husband Offset Are Not Together Anymore: ‘I Guess We Fell Out of Love’

Both Cardi and Offset are in Miami for Art Basel. A few days ago, she shared photos of her and her now-estranged husband kissing at a recent Lakers game.

Also on Wednesday, the newly single “Be Careful” rapper shared the first photo of Kulture on Instagram, writing, “My heart.”

Model Summer Bunni, the woman accused of coming between Offset and Cardi B, issued a tearful apology to the “Drip” rapper on Wednesday, claiming responsibility for her actions.

“I have not messed with Offset since he’s had his baby,” she claimed in a video sent to TMZ. “I didn’t know how serious this marriage was. A lot of girls would just deal with this situation and just be like, ‘Yo, I’m the reason they’re getting a divorce.’”

“I feel ashamed,” she said in part. “It’s a lot, but just coming from me and to Cardi B and to our fans, to her family to her situation, these were never my intentions and I never wanted to break up a happy home.”