Daniel Boulton, 30, ran 30 miles from a hostel in Skegness to Louth, Lincolnshire to kill Bethany Vincent, 26, and her nine-year-old son, Darren Henson.
The court was told that Boulton had been banned following Mrs. Vincent’s complaint, and she had developed a “hatred” for Darren.
Boulton ‘swam for hours’ outside her home on High Holme Road before being stopped several times at 8 pm on May 31 last year.
He then led the police on a 24-hour search with several pictures showing how armed officers arrested him on a farm near Louth.
Boulton tried to claim that he was on “autopilot” at the time of the murders, but jurors denied his defense of losing control.
He was sentenced to life in prison, Judge Pepperall said there was a possibility he would not be released.
The judge told Boulton: “I’m sure you focused on Darren because of your hatred and you were inspired by his autism.
“I am sure you are a violent and very dangerous person and you pose a constant risk of further violence and possibly murder.
“You killed a tireless skill shortly after entering the house.
“You acted calmly, fearfully and efficiently … you intended to kill, you knew what you did.”
Boulton’s relationship with Mrs. Vincent began on Tinder, but in late March 2019 he broke down and eventually received orders not to make contact with her.
Over the holidays, Boulton sent him nearly 900 messages, including: “You ruined my life and I said I ruined your life.”
The court heard that he had previously told a Salvation Army aide that he wanted to erase the “bloodline” in Mrs. Vincent’s family.
Prosecutor Katherine Goddard told QC that despite two restraining orders, Boulton “maintained contact with Bethany – by phone, text, social media, and unannounced and uninvited home visits.”