As Sean slipped away in the hospital, doctors approached his family about organ donation.
“Honestly, when they asked if I wanted to organ-donate, as a mother, I said ‘No,’ because I felt like it made it that much realer,” Rivera said.
But Rivera prayed, spoke to her pastor and began thinking of the other families her son could help.
"I just didn't want to be selfish and say, 'Forget those other kids. It's all about mine,'" Rivera said. "And through prayer and thinking about that pain, I just said, 'OK, let's do it.'"
On Apr. 1, Sean's family bathed him, prayed over him and said goodbye. They wept as his hospital bed was wheeled away before surgery.
Sean's heart, liver, pancreas and kidneys were donated to four children, Rivera said.
A jet flew Sean's heart to Boston, where Carlos Rolon had been at Children's Hospital for nearly eight months straight. Born with a heart defect, Carlos had been on the transplant waiting list for more than four years.
Carlos received his new heart and became stronger than ever, finally leaving the hospital last month for his home in Worcester.
"He's doing great," his mother, Sheena Cossette told WFXT-TV days after his homecoming. "He's doing absolutely amazing. They said his recovery is going well."
Cossette calls Carlos's heart donation a "miracle" for her family, but she has been praying for the donor and their family all along, acknowledging her son's gift of life was only possible through the other family's tragedy.
Within days of Carlos's transplant, Cossette wrote to Rivera, thanking her for her generous decision, Rivera told WFXT-TV. The two have since connected on social media, learning about each other's little boys.
"Carlos and Sean would've been best buddies, because it seemed they were so much alike," Rivera said, in tears. "I look at pictures of Carlos, and I sometimes see my son's smile, because he just looks so sweet."
Rivera plans to meet Carlos one day and tell him about their hero.
“I can’t wait to meet the little boy who has my son’s heart,” Rivera said. “Because it was a good one.”
Sean and Carlos are two little boys who share one heart. One is making the most of his second chance at life. The other, his mom says, is in an even better place.
"God says store up your treasures in heaven,” Rivera said. "And I have a great treasure there.”