A mother of five from Bridgend died after doctors diagnosed tuberculosis meningitis as a migraine.
Lissa Beechey, 39, was left bedridden by tiredness and crippling headaches and with eyes so sensitive she had to wear sunglasses to block out the light.
Despite her GP referring her to hospital querying meningitis, doctors told her she had a migraine and to take paracetamol.
She died 10 days later at University Hospital of Wales in Cardiff.
Simon Aberstone, Ms Beechey's husband, said: "I'm still so angry that this was allowed to happen.
"You don't rule out TB until you've tested for it and if just one doctor had followed the correct procedures and given her the right medication then Lissa would still be here.
"She had time for everyone, especially when they needed her help. We used to call her the Mother Teresa of Bridgend," he added.
"Even I didn't realise how many people's lives she touched until her funeral. It was incredible, there wasn't even standing room."
Tuberculosis meningitis - the symptoms of which include fatigue, headaches, neck pain and sensitivity to bright lights - affects just 150 to 200 people in the UK each year.
Ms Beechey showed all of the symptoms, but was discharged from Bridgend's Princess of Wales Hospital hospital in September 2015, only to return to A&E 10 days later in a confused and disorientated state.
Doctors also ruled out TB meningitis, despite an X-ray from three months earlier showing shadows on her lungs.
She died on 1 October 2015, after being transferred to the University Hospital of Wales in Cardiff.
Abertawe Bro Morgannwg University Health Board reached an undisclosed out of court settlement with Mr Aberstone.
A spokesman for the health board said: "We would once more offer our sincere condolences to Ms Beechey's family for their sad loss, and apologise for the shortcomings in her care."