How Naya Rivera and Ryan Dorsey's Families Celebrated Josey's 5th Birthday

"They want him to grow up surrounded by love," a Ryan Dorsey source tells PEOPLE

It’s been nearly three months since Naya Rivera tragically drowned, and while her sister Nickayla and ex-husband Ryan Dorsey continue to mourn the Glee star, they’re trying their hardest to be strong for her son Josey.

Last month, both Rivera and Dorsey’s families came together to celebrate Josey’s 5th birthday. “Everyone is trying to make the best of the sad situation,” a Dorsey source tells PEOPLE.

“They want to be strong for Josey. He needs to focus on things that normal 5-year-olds do, like learning to read. This is Ryan and Nickayla’s only focus: They want him to grow up surrounded by love and with people that really care about him every day," says the source.

• For more about Ryan Dorsey and how he's raising son Josey following ex-wife Naya Rivera's death, pick up this week's issue of PEOPLE, on newsstands Friday

(L-R) Naya Rivera, Ryan Dorsey, son Josey. Ryan Dorsey/Instagram

Ryan Dorsey, Nickayla Rivera. getty images (2)

On July 8, Naya, 33, went missing during a boat excursion with her son at Lake Piru in Ventura County, California. Josey later told investigators that he and his mother went swimming and after she assisted him back onto the boat, Naya cried out for help and disappeared underwater. Five days later her body was found. The cause of death was ruled an accidental drowning.

Naya Rivera and son Josey. Big Sean/Instagram

While Naya's sister is presently living with Dorsey, 37, a source told PEOPLE last month that "there is nothing romantic going on between Ryan and Nickayla."

“Ryan is a great dad, but Josey needs a mother figure in his life too,” says the Dorsey source. “Nickayla loves him so much and is amazing with him. Ryan knows that Josey will thrive with her around.”

While the source adds that “Ryan has days when he very much struggles,” having support from Naya’s sister has offered relief and comfort. “It helps him that he’s not alone with Josey. He’s very grateful for her.”