Tarek and his wife, Heather Rae El Moussa, welcomed their baby boy last month.
"Christina congratulated us, of course, and she’s very happy for us," Tarek tells the outlet.
Tarek and Heather began dating in 2019 and got engaged the following year. They tied the knot in October 2021 and announced they were expecting their first child together in July 2022. Heather gave birth on Jan. 31.
When ET spoke with Tarek and Heather in December, the couple opened up about co-parenting with his ex.
"Christina has been incredible to stepparent with," Heather said. "We communicate well. The kids are number one to us, that's the most important thing. It's been four years and I think we're in the best place we've ever been."
"We work together and that's the most important thing," she added. "We're raising good humans and we want to continue to do that. We feel like communication with each other, it's the most important thing. If people could just learn to co-parent well, your life will be so much easier, I promise you. That's what I've really learned in this journey."
As for Heather and Tarek's son, the couple initially shared pics of the tot without showing his face, before finally unveiling the newborn in February and revealing his name to be Tristan Jay El Moussa.
"Having my own and carrying him and then going through the labor… it's just such a beautiful thing that the female body can do," Heather tells Us Weekly, with Tarek adding that Tristan's birth was "just such a beautiful thing."
When ET spoke with the couple ahead of Tristan's arrival, Tarek gushed about becoming a dad again.
"Starting over isn't something that I thought I'd be doing," he said, "but life throws curveballs at you, and I couldn't be more excited, actually."