Brad Pitt reportedly "stormed out" of a meeting with his children.
The Allied actor is said to be concerned his estranged wife Angelina Jolie is trying to turn their six kids - Maddox, 15, Pax, 12, Zahara, 11, Shiloh, 10, and eight-year-old twins Knox and Vivienne - against him and have even stopped calling him "daddy".
And Kris Herzog, a bodyguard who works for both the family and Angelina's father Jon Voight, admits the 52-year-old star's two supervised visits with his brood have not gone well.
He said: "Brad is so angry. From what I've heard from Brad and Jon, even the kids are turning against him.
"He's alleging they won't even speak to him and they won't call him Daddy or Father.
"They've had two meetings with Los Angeles family services and in both none of the kids would talk to him.
"He stormed out of the second one really angry, it was the straw that broke the camel's back. This fight is going nuclear now."
Kris has also claimed Brad has already moved on from Angelina and is secretly seeing someone else.
He said: "He's started seeing another famous actress. She is a personal friend of mine and has told me they are sleeping together.
"I can't disclose who it is but she is almost as big as Angelina."
Despite the Fury star's frustration with his estranged spouse, he is unwilling to play dirty in their custody battle because he doesn't want to upset the children further.
A source told Grazia magazine: "Angelina is not the saint she is making out to be and Brad has a lot of things he could say in response to all the mud-slinging that has come his way from her people.
"But he's biting his tongue because the kids are his main interest and he never wanted to play dirty.
"Angelina still believes Brad is not fit to have joint custody and has hinted she'll provide more evidence during their legal battle. She has no intention of letting those kids go."
- Bang Showbiz