Dorsey says the couple’s 9-year-old son still “feels like he could have saved her.”

Ryan Dorsey is ready to speak about the sudden death of his ex-wife, Naya Rivera.

For the first time since the Glee star and mother of his child died in a tragic boating incident nearly five years ago, Dorsey has opened up about the devastating call that started it all. Dorsey revealed that he was in a supermarket when he learned from Rivera’s stepfather that she had gone missing while swimming with their then 4-year-old son, Josey.

“I instantly said, ‘What do you mean? She knows how to swim,'” Dorsey recalled in a candid new interview with PEOPLE. “He said, ‘They jumped in, and Josey got back on, and they’re trying to find Naya.’ I collapsed into a pallet of drinks. I didn’t know what to think, but I feared the worst.”

Dorsey, who was in Big Bear Lake, Calif., for a friend’s birthday party at the time, immediately jumped into his car and sped 145 miles to Lake Piru so that he could reunite with his son.

“I drove 100-and-­something the whole way with my four-way hazards on, chain-smoking cigarettes — and I don’t even smoke, really — and just crying,” he said. “I just wanted to get to Josey.”

Rivera’s death would not be confirmed until several days later on July 13, 2020, when her body was recovered after a weeklong search. She went missing after embarking on a boating trip with Josey, who was found safe, asleep in a lifejacket, on the drifting boat. According to investigators, Rivera was able to help her son get back into the boat but could not do so herself.

“It was the worst five days of my life,” Dorsey said of the waiting for news while officials searched for Rivera. “There was a fear: ‘What if we don’t find her?’ It was just awful.”

He added, “If we’d have lost both Naya and Josey, I don’t know how I would continue on with my life. I don’t know what I would’ve done, but I’m sure it wouldn’t have been good.”

As for what his son recalls of the traumatic day, Dorsey became emotional while reflecting on the details Josey has shared with him.

“He said that the last thing she said was his name, and then she went under, and he didn’t see her anymore,” Dorsey said, with tears in his eyes. “It just rocks my world that he had to witness her last moments.”

He also spoke to Josey’s resilience in the wake of the tragedy, adding that though he is “such a happy kid,” the loss has also taken a toll on him. “I treat him differently than I would a normal kid because of what he’s been through,” Dorsey said, noting that his 9-year-old son still feels guilt over his mother’s death. “Something he’s said over and over is that he was trying to find a life raft, and there was a rope, but there was a big spider on the rope, and he was too scared to throw it. I keep reassuring him, ‘Buddy, that rope wasn’t going to be long enough.'”

Still, Dorsey said his son can’t forget the detail “because he feels like he could have saved her.”

While he described the incident as a “freak occurrence,” Dorsey admitted that he, too, ponders how things would have gone if he had been present. “I probably would have jumped in, and I like to think I would’ve saved the day,” he said. “But on the other hand, I think maybe something bad could have happened to both of us. I don’t know.”

Dorsey married Rivera in 2014, and they welcomed their son the following year. They later hit a rough patch, with Rivera filing for divorce from the Ray Donovan star in 2016, but a month later she had a change of heart and called off their split. The couple ultimately went their separate ways in 2018, with Rivera again filing for divorce. Afterwards, they came to a joint-custody agreement and, Dorsey said, “never had any real turmoil” as co-parents, always putting their son’s needs first.