How Ryan Dorsey Is Keeping Naya Rivera's Memory Alive During the Holidays for Son Josey, 5

Ryan Dorsey is focused on keeping Naya Rivera's memory alive for their son Josey.

Five months after Rivera tragically drowned at age 33 during a boating trip with her young son, a source tells PEOPLE that Dorsey, 37, is "doing okay" as he continues to grieve the loss of his late ex-wife while raising his little boy.

"Ryan is very much about keeping Naya's memory alive. He often tells Josey, 'Mommy would have liked that,' " the source says.

As a way to keep her close to their hearts, Dorsey and 5-year-old Josey "look at pictures together and Ryan reminds Josey about all the fun that he had with his mom. Ryan is very focused on being the best dad," says the source. "He is doing a great job."

On July 13, Rivera's body was found in Lake Piru in Ventura County, California — five days after she disappeared during the boat excursion. The Glee star's cause of death was ruled as drowning and the manner of death was determined to be an accident. She was laid to rest on July 24.

Following her death, Rivera's sister, Nickayla, moved in with Dorsey and Josey to help care for her young nephew.

"Along with Nickayla and both of their families, Ryan works hard at making things the best possible for Josey. They are getting ready for Christmas now," the source says of Dorsey and Nickayla, whose families both plan to spend Christmas together. "Ryan and Josey have been decorating."

Their upcoming joint-family Christmas celebration will come just over a month after Dorsey filed a wrongful death lawsuit on behalf of Josey.

According to court documents obtained by PEOPLE, Josey is suing Ventura County, California, the county's Parks and Recreation Management, and the United Water Conservation District for wrongful death and negligent infliction of emotional distress.

The lawsuit claims Rivera's death was preventable and states that the boat she and her son rented from Lake Piru did not have the proper features and equipment necessary to comply with U.S. Coast Guard safety standards.

Spokespersons for Ventura County and the United Water Conservation District did not respond to PEOPLE's requests for comment at the time.

"[The boat] was not equipped with a safely accessible ladder, adequate rope, an anchor, a radio or any security mechanisms to prevent swimmers from being separated from their boats," the complaint states. "Disturbingly, later inspection revealed that the boat was not even equipped with any flotation or lifesaving devices, in direct violation of California law, which requires that all pontoons longer than 16 feet be equipped with flotation devices."

According to the documents, along with Rivera, who had "strong" swimming skills, "more than two dozen people have drowned in Lake Piru since 1959." (Ventura County Sheriff Sgt. Kevin Donoghue previously confirmed to PEOPLE that there have been prior drownings at the lake.)

As to why Dorsey filed the suit, the source tells PEOPLE, "it just didn't need to happen. It's a huge tragedy and it seemed preventable."