Last Sunday morning, Celine Ben David Nagar should have been getting ready for her first day back at work after six happy months on maternity leave.

Instead, she was thought to be somewhere inside Gaza, in the hands of Hamas, and her family was 24 hours into a nightmare that is now a week long.

Celine, 32, had set out early on Saturday morning with two friends to attend the Nova music festival in southern Israel, but they turned back when they heard rockets ahead.

The group found their way to a public bomb shelter near Sderot and hid. It was from there, at 07:11, that Celine sent her final message to Ido, her husband and the father of their baby daughter, Ellie.

“Soldiers are coming,” Celine wrote. “God, it was a mistake to come here.”

Ido sped south towards the site on Saturday but the military wouldn’t let him pass. On Sunday morning, he found Celine’s car, pockmarked with bullet holes but otherwise as she had left it.

Later that day, Ido found a survivor who told him that the Hamas militants had thrown grenades into the shelter, killing Celine’s friends. But Celine had survived, the stranger said.

In the six days since, it has been all Ido has to hang on to. The only other thing he knows is that her body has not been found.

“You don’t sleep and you don’t eat and you are in a kind of crazed uncertainty,” he said, in a phone interview from his home near Tel Aviv. “You are totally helpless.”

Ido broke down in tears as he tried to describe his wife, an administrative assistant at the law firm where he works, who grew up in France and is a French-Israeli citizen.

“She is an amazing woman, a person who is surrounded by friends and love,” he said.

“And she is an amazing mother. We have a six-month old baby. This was supposed to be her one last party to enjoy before she returned to work. We agreed that I would pick her up at midnight, but she never came home.”

The community has rallied around him, with friends and relatives bringing food and milk to feed Ellie, who Celine was breastfeeding, and to help take care of her.

Much of Ido’s time is taken up with the effort to highlight the plight of the hostages. He is in a WhatsApp group with other relatives, where they share information.

Little is known about the location or condition of the roughly 150 hostages believed to have been taken into Gaza. They were seized from towns along the Israel-Gaza border as well as from military bases in the area, and they include children and babies, elderly people and people with disabilities.

Hamas said it had hidden the hostages in “safe places and tunnels”, but has threatened to kill them if civilian homes are bombed by Israel without warning.

For Ido and the hundreds of other close relatives, it is a nightmare from which they cannot wake up.

“I try to fight it in every way I can think of, I try to be optimistic and I try to think positive thoughts,” he said, through the tears.

“I want to believe that she is alive there, in Gaza, and maybe she is taking care of the children who were kidnapped with her.

“I just hope that she knows that we are fighting for her, and that she is telling herself she will come home.”