Brothers reveal anguish over father who killed their mum and sister
Lance Hart, 57, killed his wife Claire, 50, and daughter Charlotte, 19, before turning the gun on himself.
He wrote a 12-page suicide document outlining what he was thinking and planning in the weeks running up to tragedy.
In it he clearly states he is "not in his right mind" and blamed his children for what he was planning to do.
His sons, Luke and Ryan, 26, today told how they had endured a "lifetime of struggle" with his controlling behaviour.
Speaking on the Victoria Derbyshire Show, Luke, 27, said: "He had nothing to live for other than killing us.
He had nothing to live for other than killing us
"Someone like our father was a terrorist. He was planning to kill all of us three weeks before killing them.
"When it's your own father… the anger is inexplicable. It's so complicated and horrible and the media treated it like a one-off, but for us it was a culmination of a lifetime of struggle.
"He was vitriolic and a bully who would be verbally abusive and threaten us.
"In a way you feel pity and sympathy and feel weakness and think he needs help. When we tried to get him help, he'd refuse.
"He held traditional masculine beliefs and a lot of people think that is normal.
"He thought he owned us and saw us as protected by him but we were entirely oppressed by him."
Get Quotes on Home Insurance
Lance shot his wife and daughter before turning the gun on himself
Mrs Hart had packed her bags and walked out on July 14 last year because she 'had enough' of her 'selfish' husband, who spent the next five days plotting murder.
Lance sat in wait for Claire and Charlotte at the Castle Leisure Complex in Spalding, Lincs., on July 19.
But as they approached him, who was stood by his car in the car park, he pulled the shotgun out.
They were between one to two metres from him when he pulled the trigger.
Claire and Charlotte were shot in the stomach. Both women fell to their knees and then to the ground.
Horrified witnesses rushed to help and found Claire and Hart dead but Charlotte was still alive.
Before she died she managed to say: "It was my dad who shot me."
An inquest into their deaths in October last year heard how police found a sick 12-page document Hart left which blamed his children for his actions.
It was on USB stick found in his car labelled "To whom it may concern".
The sons told how they had endured a 'lifetime of struggle' with his uncontrollable behaviour
On it, Hart said he felt as if his family had been in a car crash and he wanted revenge.
He blamed his children, especially his son Ryan for making matters worse between him and his wife.
He said: "Karma is coming, Karma is a bitch, now you all lose."
Adding: "Ryan, you know what you have done… You got what you wished for."
The court heard evidence from the police that Lance had been adding to the statement over a number of weeks before the shooting.
One of the last entries spoke of him enjoying his last meal, his favourite meal, paella, with some wine in the summer sun.
He continued: "I know my mind is screwed, I'm completely screwed, right or wrong I had to do it.
"You completely destroyed my life without giving me a chance so I will destroy yours."
He also said: "I love you all, I always have, always will."
Charlotte's last words were: 'It was my dad who shot me'
Before signing off: "Revenge is a dish best served cold, karma is a bitch."
The court heard Lance had to be identified by his fingerprints after suffering a shotgun wound to the head.
Luke said his mother Claire had been keeping a diary of everything his father had said and done, but "as there were no bruises" they never felt it was something they could take to the police.
He said: "Even if we did, what would they have done? They wouldn't have taken him out of the house.
"He would have broken any restraining order. The problem is you can only protect people by having universal societal beliefs."
Concluding the inquest last year, coroner Paul Cooper revealed he had a single barrel shotgun so had to repeatedly load it as he killed his own family.
He said: "He knew exactly what he was going to do. It was a single barrel shotgun, so it was not a question of him just shooting his wife, he then had to unload it, put another cartridge in and shoot it again.
"In my view, this was a cold, calculated, scheming man who went out and deliberately murdered his wife and daughter.
"If he had lived… he would have been charged with murder, unfortunately he didn't live to face the consequences of his actions. He took his own life."