Sundahl recently underwent emergency surgery, and he told The ENQUIRER that Britney kept a round-the-clock vigil at his hospital bedside. He also reveals that he’s been subpoenaed by her estranged husband Kevin Federline to testify in the couple’s custody battle.

“Britney is my rock,�? Sundahl told The ENQUIRER. “When I was in the hospital, she sad with me and held my hand all night long. She even sang and hummed to me while I was practically unconscious.

“I love being around her. She’s a sweet, caring girl and a good mom. And she’s good with my 16-year-old dog Powder, too. That’s important.�?

Sundahl, a wealthy 38-year-old real estate investor, is chairman of Britney’s Alcoholics Anonymous chapter in Los Angeles. He met the 25-year-old singer when she sought drug and alcohol counseling from him after her rehab stint at Promises in Malibu.

Their relationship soon evolved into romance- and now Sundahl says he’s been subpoenaed by Kevin Federline’s lawyers to testify against Britney in the custody battle over the couple’s two young songs.

Sundahl says he doubts that he’ll be called to testify because of his “relationship�? with Britney- who was at his side at Kaiser Permanente Medical Center in Los Angeles while he recovered from emergency surgery for an obstructed bowel on June 18.

“Britney showed up two days later with her bodyguard and an overnight bag. She was wearing a while jumpsuit, and a hat and big glasses,�? an insider revealed.

‘She asked for a recliner and pulled it right up next to John’s bed. She held his hand, and when he writhed in pain, she said: ‘It’s OK, honey, Britney’s here.’ She hummed and sang to him to calm him down. When John fell asleep, Britney watched TV or read. When she was tired, she cuddled up in a blanket on the recliner and fell asleep.�?

The next day Britney went home to shower and change clothes, but she was soon back at the hospital, said the source.

“Doctors told John he had to get out of bed and start walking. Britney helped him out of bed and helped him walk around the floor,�? said the insider. “But before she left his room, she put on her hat and sunglasses so no one would recognize her. Later she ordered take-out Chinese food, but before she ate anything she help a spoon to John’s mouth and fed him like a baby.�?

Sundahl was discharged a few days later, but says his doctors have warned him to cut back his work schedule. He plans to take a year off to rest and travel.

“When Britney’s not working, she’ll travel with me,�? he told The ENQUIRER.