A worker for the Department for Work and Pensions has been suspended after a disabled woman said a benefits assessor laughed at her and threatened her son.
Police also said they were investigating criminal damage at the Cardiff home of Cheryl Matthews.
Mrs Matthews said the assessor, employed by Capita, dismissed claims she had felt suicidal as "irrelevant".
Capita said a worker had been suspended, it had apologised to Mrs Matthews and offered her compensation.
She said he also shouted at her 22-year-old son when he told him to leave.
Mrs Matthews, who is 45 and has long-term health conditions, said Capita had also paid her £600 in compensation within hours of lodging a complaint.
She has the painful condition fibromyalgia, cranial hypertension, and a degenerative spinal condition.
She said she had already been receiving a Personal Independence Payment of £327 a month but needed a new assessment, carried out by Capita on behalf of the Department for Works and Pensions (DWP).
"Capita wrote to me and offered to carry out the assessment in my home," she said.
"It was a huge relief as my anxiety and poor mobility make it difficult to get around."
She said the assessment took place in her bedroom on 16 October, but the interview deteriorated rapidly.
"I tried to explain that a few weeks earlier I'd been in so much pain, I wanted to take my life," she said.
"I'd gone as far as visiting the GP and begging them for pills because I didn't want to be here any more.
"The assessor just laughed, saying 'irrelevant, irrelevant, irrelevant'."
Mrs Matthews said her 22-year-old son intervened and told the assessor to leave.
She said the man pushed her son and as he went downstairs, told him: "You want a fight do you mate? I can give you a fight."
Mrs Matthews said the man then kicked a child safety gate kept across the front door "out of the frame" and into the garden, yelling at her son: "I'll be back for you mate - clearly you want a fight."
In a statement, Capita said it had apologised to the family, suspended an assessor "pending an investigation" and offered Mrs Matthews compensation.
South Wales Police also confirmed it was investigating an allegation of criminal damage at the property, but added no arrests had been made.
A DWP spokesperson said: "We take these allegations extremely seriously. The assessor in this case was immediately suspended while Capita is carrying out their investigation.
"We expect the highest standards from our providers and all claimants must be treated with dignity and respect."