Peter Andre reunited with Katie Price after his step-son Harvey was taken ill.
The Australian singer dashed to East Surrey Hospital in Redhill, England, to be with seven-year-old Harvey - who suffers from septo-optic dysplasia and autism - after learning he had contracted suspected swine flu.
A source said: "Harvey had a massive temperature and couldn't keep any food down. More worryingly, his breathing was also a huge concern and there was no option but to urgently seek medical advice.
"The doctors weren't taking any chances. If he doesn't get any better, he might be there for a while. It could be complications from potential swine flu. He's a very poorly young man."
Katie is said to be "frantic" with worry that Harvey may not show any immediate improvement and broke down in tears after speaking to doctors.
She reportedly told a friend: "I have to be there for Harvey. He's my little angel and he needs his mummy."
Harvey's hospitalisation marks the first time the couple - whose divorce was finalised last month - have been together since they split up in May this year, but friends insist Peter would never have missed the chance to stay with Harvey, whose father is soccer player Dwight Yorke, despite his fraught relationship with the glamour model.
A pal said: "He is very worried and has gone to hospital because he wanted to be with Harvey as well."
Katie and Peter also have a son Junior, four, and daughter Princess Tiaamii, two.