The holiday marks Kristin Cavallari's first since filing for divorce from husband Jay Cutler

Kristin Cavallari is celebrating Mother's Day with her brood!

On Sunday, the Very Cavallari star, 33, posted a photo of herself and her three kids — sons Jaxon, 6, and Camden, 7, and daughter Saylor, 4 — at the beach to mark the holiday.

"Everything made sense once I become a mom to these 3. Being their mom is the greatest gift. Happy Mother’s Day to all of the moms out there," she wrote alongside the happy family photo.

The holiday marks Cavallari's first since filing for divorce from husband Jay Cutler.

On Sunday, Cutler shared a tribute to Cavallari on Instagram. "Happy Mother's day to all the moms. These 3 little ones picked a good one," he wrote, along with a photo of their kids.

Kristin Cavallari
Kristin Cavallari
| Credit: Manny Carabel/Getty

PEOPLE previously reported that Cavallari would spend Mother's Day with her children, per her custody agreement with Cutler.

"Mother’s Day and Father’s Day shall begin at 3:00 p.m. on the Friday immediately prior to the holiday, or 3:00 p.m. if there is no school, until return to school the Monday immediately after the holiday or at 9:00 a.m. if there is no school," the agreement states.

The two announced that they were divorcing last month, and a source confirmed to PEOPLE last week that they had reached a custody agreement.

Cutler also agreed to release the funds for Cavallari to purchase her own home, the source said. Prior to this agreement, Cavallari claimed Cutler was preventing her from buying a new house with her own money unless she agreed to share joint custody with him.

Documents obtained by PEOPLE state that both parties "have entered into a Permanent Parenting Plan that they attest is in the best interest of their minor children and ask the Court to approve and adopt the same as its Order."

Cavallari and Cutler agreed to be named "joint primary residential parents," each spending 182.5 days with the kids a year and alternating time on a week-on, week-off basis, according to the documents.

Jay Cutler and Kristin Cavallari
Kristin Cavallari and Jay Cutler
| Credit: Jason LaVeris/Getty

They will alternate Easter and Thanksgiving, as well as fall and spring breaks, and will split the Christmas holiday. The agreement also notes that each parent will have the right to two phone calls and two FaceTime or Skype calls per week while the children are with the other parent.

Last week, Cavallari celebrated their son Jaxon's birthday with a sweet Instagram tribute.

“Happy 6th birthday my little man. Jaxy, you have such a sweet, sensitive side yet have the ability to make everyone laugh with your incredible sense of humor and wit,” she wrote in the caption alongside two pictures of her embracing her son. “You light up a room and make this world a better place. I’m so thankful to be your momma. Love you forever angel.”