Roger Pratt, 62, a retired engineer, died and his wife Margaret was injured after three armed men climbed aboard their yacht moored off St Lucia on Friday.
Mrs Pratt, who retired as a management consultant to go on the round-the-world trip, celebrated her 60th birthday just days before the incident.
The couple had planned to set sail for the next stage of their journey the day before the attack but were prevented from leaving by a bureaucratic hold-up.
Mrs Pratt's sister Jenny Riley, a teacher from Beccles, Suffolk, said the family had been left "totally shocked and shattered" by the news.
She said Mr Pratt had been preparing for the voyage for many years and was extremely safety-conscious.
Mrs Riley said she had spoken to Mrs Pratt by telephone and her injuries were not life-threatening and she was recovering well. She has returned to the yacht.
"She has been badly beaten up but she will pull through," she said.
"It's a shocking and tragic end to their dream and we're all coming to terms with it as best we can. Margaret is very strong and she's very busy, there's a lot to do. At the moment she is concentrating on that and that focus is helping her keep it together."
Referring to the three men held over the attack, she said: "Margeret's life has been turned upside down but ultimately these three men's lives are over as well, so it's tragic all round."
Mrs Riley and her husband Bryan visited the couple in Martinique over Christmas.
"They had been planning the trip for years and sailing across the Atlantic to explore the Carribean was Roger's dream," Mrs Riley said. "They were both experienced sailors and had sailed dinghies and keel boats since they were children."
She added that support from the Foreign Office in London and St Lucia had been vital to Mrs Pratt.
Three men have been detained in connection with the incident, and a post-mortem examination was due to be carried out yesterday.