Charlie, who suffered from a rare genetic condition, died on Friday after his life support was turned off.
His parents Connie Yates, 31, and Chris Gard, 33, spent the day at home planning his funeral following a lengthy legal battle over his treatment.
The family’s spokeswoman Alison Smith-Squire revealed she broke down in tears after Connie broke the news about Charlie’s death.
She told The Sun: “Connie, Chris, and myself have gone through an extraordinary journey together.
“When Connie WhatsApped me and said ‘He’s gone’ I wept.”
Connie and Chris want to use £1.3million of donations to fund a campaign to prevent other parents suffering the same nightmare ordeal they went through with Charlie.
A family friend said: “They wanted to gather their thoughts and start the grieving process.
“They have the funeral to plan and they don’t know yet whether they want a private service or something more public.
“They also want to start a charity foundation with money people donated.
“They will be looking to campaign for changes to the legal and health system after their nightmare experience.
“They just wanted to hide away from the world for a day so they could grieve in private.”
Charlie’s rare genetic condition caused progressive brain damage and muscle weakness.
The 11-month-old baby became the subject of a bitter dispute between his parents and doctors over whether he should be taken to the US for experimental treatment.
At odds with Great Ormond Street Hospital, Ms Yates and Charlie’s father Chris Gard had wanted to take their severely ill son to the US for treatment prompting a legal battle.
Dr Stephen Playfor, clinical manager for the Paediatric Intensive Care Unit at the Royal Manchester Children’s Hospital, said he believed children were suffering unnecessarily due to long legal disputes.
He said: “Cases such as these are becoming more common as medical advances mean there are more treatments available for very sick children who may never lead independent lives.
“It is awful when you have children lying for months in intensive care units when they are suffering and can never have any meaningful quality of life.”
“A protracted legal battle can cause huge damage to the patient’s families and staff, as well as being very expensive for all concerned.”