Cancer survivor Michael Douglas has claimed Catherine Zeta-Jones broke down under the stress of his illness because of her “Welsh background”.Douglas, 66, was given the all-clear from throat cancer in January.But his 41-year-old wife was admitted to a US clinic for five days earlier this month where she was diagnosed with a mild form of bipolar disorder.It is thought it was brought on by the strain of her husband’s fight against cancer and sticking by him when his son Cameron was jailed for serious drug offences last year.At the same time, she has also been at her husband’s side as he faced multi-million-dollar legal action from ex-wife Diandra.Speaking on the Oprah Winfrey show in the US to an audience of millions, Douglas said while he “got on with it” his wife showed typical British...