The mother of a terminally ill baby says a decision to remove life-support means that her parental rights have been "stripped away" by "strangers".
Connie Yates says that despite this week's "heartbreaking" High Court ruling, she cannot bear to let her eight-month-old son Charlie Gard go until every medical avenue has been explored.
Charlie, who is being cared for at London's Great Ormond Street Hospital, has a form of mitochondrial disease (RRM2B), which causes brain damage and progressive muscle weakness.
An appeal against the judgement is being considered.
Ms Yates, 31, told the Daily Mail that she and her partner, Chris Gard, 32, are simply trying to be good parents.
"This isn't about us being selfish, keeping him alive because we can't bear to let him go," she said.
"It is because if we did not fight for this chance, we will have to live with the 'what if' for ever.
"It's that 'what if' which for us would be so unbearable."
Connie and Chris have raised more than £1m to take Charlie to America to undergo a treatment called nucleoside.
'We are absolutely convinced he is not in pain," Ms Yates said.
"When he feels our presence, he tries to open his eyes as much as he can, so we do not believe he is blind.
"Because we know our son, we do not believe Charlie has the structural brain damage doctors say he has.
"If there is even the slimmest chance of a treatment working, and the doctor in the US told us he believes there is, what loving parent would not take that chance?"
She added: "We would never have sought this if we thought it would bring Charlie more pain.
"But why is it so different from a child with cancer having painful and distressing chemotherapy which might not work?"
While Ms Yates admits the treatment she and her husband want to try in the US has not been tried "on an animal or human with RRM2B" it has, she said, worked for people with a similar condition, TK2.
She told the Mail: "One little boy, who has TK2 and was the first to try nucleoside therapy in America, is now aged six. Although still ventilated, he is well enough to enjoy trips to the movies and zoo.
"He grows stronger every day. His parents say they took the same slim chance and have absolutely no regrets."
Ms Yates said that even contemplating saying goodbye to Charlie is extremely painful.
"When I think about willingly turning off Charlie's life support, with him dying in our arms, I cry uncontrollably," she said.
"It's so hard because he is so stable - he is growing before our eyes. Every day he looks more and more like Chris.
"Letting Charlie go is something we would have faced up to, would have prepared for and accepted, if we felt we'd exhausted all chances of treatment."