On Saturday, the 38-year-old actor posted photos of his ex-wife, and Josey, on Instagram, penning a letter to her in the caption.
"Today…A year ago we laid you to rest. I still can't believe it," Dorsey shared.
As the Big Sky actor continued, he said their 5-year-old son is "doing ok," but misses his mom.
"Our boy has grown so much," he continued. "He's such an explorer, so inquisitive. He's sweet, so funny, and his laugh always lights up the room. He's an intuitive soul to say the least. To know him is to love him, everyone that meets him is always smiling. He's doing ok. He's such a resilient strong kid. He misses you but knows he'll see you again, and the invisible string is something that's helped us out during this ever-evolving transition of your time with us on earth that was unfairly & for reasons we'll never understand cut short…too soon."
In the photo collage, Dorsey included a newer image of their son holding his thumb up. The actor explained the child's gesture was a tribute to his mom.
"The thumbs up…only [s]eemed right. I remember the first time he did it back to you. At jujitsu, you gave him a thumbs up and he returned the gesture…it was so sweet," he wrote, before addressing why he was sharing the Rivera tribute on Instagram. "Maybe it's silly and doesn't make sense to be doing this on IG and putting this out there, but so is this whole thing. So there's that…"
Dorsey concluded by noting Josey is, "being raised right, and he's got a lot of family and people around him that love him, and you. 🖤💔💙🖤"
Rivera died as the result of drowning on July 8, 2020, in Lake Piru, outside of Los Angeles. She had been on a boating excursion with her son at the time. Rivera was 33.
Earlier this month, many members of the Glee cast paid tribute to the actress on social media, including Heather Morris, who revealed she got a tattoo inspired by her late friend.