Mairead Philpott has said she was stunned when Lisa Willis left Mick Philpott and the family home with her five children.
Asked at Nottingham Crown Court: "On a scale of 1-10 how surprised were you that Lisa left?" Mairead replied: "10".
Mairead Philpott said she and her own six children were left distraught and "heartbroken" by the group's departure in February 2012.
She told the jury her children often went to bed crying, had nightmares, and some even wet their beds after they left.
More top news
The singer ended speculation over who would perform by saying "the rumors are true" to her 63 million Twitter followers on Friday morning.
There will be lighter winds for all of us than yesterday, although it will still feel cool.
Senior fashion analyst at Mintel Tamara Sender said: "For the first time ever sales of trainers have overtaken high heels."