Allen Berezovsky/Getty; christina haack/ instagram
Happy birthday, Hudson London!
"Happy 2️⃣ Birthday Hudson!!" Haack, 38, wrote alongside a photo of her youngest about to eat a birthday cupcake.
"Such a sweet, active and smart boy," she said of Hudson. "He loves to try and figure things out for himself and has this mischievous look on his face while doing it haha. He's talking a lot already but his favorite word in our home is 'Cash' 🐶. We love you!"
Sharing several photos and videos from Hudson's birthday celebrations, Anstead, 42, wrote on Instagram: "Now THAT was a PARTY!!!"
"We danced, ate cake, opened presents, ate more cake and it ended in a bonkers water fight and soggy cake! Perfect!" the Celebrity IOU: Joyride host continued. One video he shared showed Hudson pouring a bucket of water on his dad, while a candid photo caught Anstead smiling as he held Hudson wrapped up in a towel.
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
"Happy birthday Hudzo! TWO!! You are one loved little boy! ❤️ x" Anstead added.
Haack and Anstead married in December 2018, and welcomed Hudson the following September. The pair announced that they were splitting in September 2020, and finalized their divorce in June.
Both are parents from previous relationships: Haack shares daughter Taylor, 10, and son Brayden 6, with ex-husband Tarek El Moussa, and Anstead shares daughter Amelie, 17, and son Archie, 15, with his first wife, Louise Herbert.
ant anstead/ instagram Ant Anstead holding son Hudson
Since their breakup, Haack and Anstead have moved on to new relationships. The Christina on the Coast star is currently seeing Austin-based realtor Joshua Hall, while Anstead is dating Renée Zellweger.
A source told PEOPLE last month that Hudson remains Anstead's "focus" as he's dating the 52-year-old actress.
"Even when Renée is around, his son is the center of attention," the source said. "They do beach outings, go for ice cream and other child-friendly activities."