Lisa Willis has said she asked her sister Amanda for help on Facebook because she wanted to get out of the relationship with Mick Philpott.
She deleted the exchanges as she went along so they wouldn't be found, although she told Nottingham Crown Court that Mick Philpott couldn't use a computer.
Ms Willis said her relationship with Amanda had ended when she moved into Mick Philpott's home on Victory Road because he wasn't happy with it and her sister didn't like him.
She said she didn't see Amanda for years before resuming contact on Facebook.
The trial has now stopped for lunch.
More top news
A similar split set up to today
The Eagles of Death Metal want to be the first to play the Bataclan when it reopens, the lead singer has said in an emotional interview.
Cheap commercial spaceflight took one giant leap closer to reality after Blue Origin successfully landed a rocket - upright - in Texas.