The "triple dose" of intensive chemotherapy intended to destroy Mrs Regnault's immune system and the abnormal cells responsible for her disease began last week, with doses gradually building to a peak this week.
Thursday is scheduled to be "day zero", the day when her harvested stem cells are reintroduced. It was a date that people who underwent the treatment referred to as their new birthday, Mr Regnault said.
The collection of stem cells had gone quicker than anticipated but it remained to be seen how she would cope with a full dose of chemotherapy, he said.
"I'm not sure how she'll be tonight or if we'll even get a call because she might just not feel like it, but to date she's been pretty good."
Mr Regnault returned from Singapore late last month and since then has been kept busy with the children, despite some "fantastic" support from friends and family.
"It's keeping me on my toes between cooking and cleaning and school lunches."
Since his departure, Mrs Regnault's family are taking turns keeping her company in Singapore.
Mrs Regnault will remain in hospital for at least another three weeks after the stem cells are replaced.