Susan Boyle was "emotionally blackmailed" by her brother for £50,000.
The 52-year-old singing sensation - who shot to fame after finishing second on 'Britain's Got Talent' in 2009 - handed over the huge sum to her elder sibling Gerry, 59, after he visited her in the US and told her he would kill himself if she didn't give him the money, her family claims.
Susan's nephew Alan Boyle, 34, told The Sun newspaper: "It was emotional blackmail.
"Susan felt like she had no choice and had to give the money to him. She doesn't deal with pressure very well and he knew the buttons to press."
Businessman Gerry, who runs entertainment company Instant Arena, is said to have wanted the money to turn an old cinema he is renting in Edinburgh, Scotland, into an impressive venue fit to hold big showbiz events.
But Susan's family are now concerned Gerry might ask the 'I Dreamed a Dream' hitmaker for more cash at a later date.
Her sister Bridie McCaw said: "In New York she hadn't spoken to him for weeks when he asked for the £50,000. She wasn't well and had a viral infection and tonsillitis. She just said she would give it to him."
Susan's niece Kirsty Foy added: "He is wildly ambitious beyond his capabilities. His track record speaks for itself."
A spokesman for the singer said: "It is true. There were threats of suicide if she did not pay yet another large amount of money."
However, Gerry has laughed off the claims.
He said: "I've heard it all before.
"I've got nothing to say. I'm actually busy on the phone to some adults right now."