Malo Myers, 33, has pleaded guilty of manslaughter and will be sentenced this afternoon.
Malo also stabbed his 14-year-old brother who was dispatched to the hospital, with "non-life threatening" injuries.
Lorna Myers, 54, from Aylesbury in Buckinghamshire, died in Wood White Drive in the town on July 7 2018.
A post-mortem examination found the cause of death to be a stab wound to the chest.
Speaking at the time Head of the Major Crime Unit, Detective Superintendent Ian Hunter said: “This is a tragic incident which has resulted in the death of Lorna Myers, injuries to a 14-year-old boy and untold impact on friends, family and the local community."
More on this as he is sentenced this afternoon.