The motorcycle star was the 2010 Irish Supersport Clubman champion and he won the 2011 Adelaide Masters.
Jacqui's heartbroken message on her Facebook page declared: "RIP bubs, can't quite contemplate how we're going to get through this, but we'll try. Xxx."
Jacqui is the first woman in RTE history to present a sports show. She co-presents Sunday Sport on RTE Radio 1 and the sports news on RTE Radio 1 and 2fm.
Television comedian PJ Gallagher, a friend of Sean, said he was "one of the nicest men in motorbikes".
Sean was considered one of Ireland's outstanding young motorcycle racing talents. He enjoyed an outstanding racing season this year and was invited to Valencia in Spain by sponsors Bridgestone to mark his triumph in the Mondello Park Supersport Championship.
He had been in negotiations to join a Northern Ireland-based racing squad for the 2012 season. His friend Declan Swanton said he had been training in a gym with him the day before the freak accident and Sean was in great form.
Cork Motorcycle Racing & Vintage Club described his death as a tragedy for the entire sport.
A club spokesperson posted that he was a "champion, great pilot, a decent and good guy. Our thoughts and prayers are with his family and loved ones at this tough and painful time".
Friends said Sean's entire family are completely devastated by the tragedy. The popular sportsman worked as a plasterer. His sister Jacqui also excelled in the world of sport, playing basketball and camogie at the highest levels.
RTE's motorsport correspondent John Kenny said: "My heart goes out to Jacqui and her family. Sean was very talented and had a bright future in the sport."
Sean was the only son of David and Mairead Hurley and brother to Jacqui and Catriona. His girlfriend Sinead O'Donovan was being comforted by family and friends today.
His Requiem Mass takes place at noon tomorrow at the Church of the Sacred Heart in Ballyheada.