Frank Giudice, 63, died Wednesday after collapsing at the home of his son and daughter-in-law, Teresa, in Towaco, New Jersey.
"They're holding it together. Joe and his dad were best friends," a rep for the Giudice family tells PEOPLE. "It's very hard and the girls have gone through a lot and continue to go through it. There's a lot of emotion going on."
Giudice family members have been posting photos in memory of Frank. Gia Giudice, 13, who's one of his 11 granddaughters, posted on Twitter, "The pain in my heart is unreal...". She also posted a photo of herself with her beloved grandfather on Thursday, calling him the "strongest man I know."
There will be a viewing Sunday at Festas Memorial Funeral Home in Towaco, followed by a funeral on Monday at St. James of the Marches. "They're waiting for some family to fly in from Italy," the rep says.
strongest man I know.. I love you nonno rest in peace 6/18/14 pic.twitter.com/Fwsasr8M3C— Gia Giudice (@TrueGia) June 20, 2014