Actor Dorsey shared a sweet snap of the "Glee" star and their son, five-year-old Josey, sharing a dessert at a diner, as he honored her memory on the sombre holiday - their first without Rivera.
"We can't say the word happy but we'll say thank you for being a mother & giving me this sweet amazing boy," he captioned the Instagram photo.
The tribute post came months after Dorsey praised their little boy for being strong. "This little boy...man...I couldn't be any prouder of someone. At such a young age, he's endured more than anyone should at 5 years old," he shared on Instagram in January.
"Without even fully realizing it, he lives the #keeppounding mantra every day with his resilience," the actor continued with a reference to Carolina Panthers' motto. "You're so strong, so brave, and so kind. I will always be proud of you and we will always #keeppounding b/c that's all we can do."
"To everyone that had a tough 2020...you will never forget it, we think about it every day and I feel for you and vibrate alongside you on that frequency...I hope you can find some way to go on with your days, to persevere - no matter how hard it is," he added. "All the love. #keeppounding."
Rivera drowned in California's Lake Piru after taking Josey on a boating trip in July 2020. Authorities suggested that the actress sacrificed herself to save her son. She was just 33.