ET has confirmed that LARRY BIRKHEAD's father has passed away. He was 66.

"He just had knee surgery then was sent home with an oxygen tank because they noticed a shortness of breath," Larry tells ET. "He was getting ready to start rehab for his knee and his lung and he collapsed in the bathroom."

The loss hits especially hard so close to the holidays, after a year of emotional ups and downs for Larry.

"I have had such a crazy year and if it weren't for the joy DANNIELYNN brings me, it would be impossible to deal with," he says. "My dad was so excited about spending the holidays. He kept calling me asking when I was coming home with Dannielynn for Christmas."

Larry fondly remembers his father's zest for life, adding: "He bragged to all the nurses at the hospital during his knee surgery that he was my dad and Dannielynn's grandfather. When they didn't believe him, he would always show them his ID with the name Larry Birkhead -- then he would say, 'but I'm the good looking Larry Birkhead!'"

ET captured Larry and his father at Dannielynn's birthday earlier this year in our exclusive video footage.

Visitation will be held tomorrow, with the burial service on Friday.