A triplet paralysed her identical sister by pushing her out of a 25ft high window because of 'volatile' sibling rivalry.
Louise Velloza, 24, and her sister Gillian lived together at hostel in Anfield, Liverpool.
After years of rows, Gillian pushed Louise from the window of the hostel.
She landed on an iron grid in front of the building and suffered a serious spinal cord injury, four fractured ribs and a punctured lung, is now confined to a wheelchair.
She now needs round-the-clock care and has been told by doctors she will never walk again.
Liverpool Crown Court heard that after the accident Gillian told her lawyer: "Tell her I love her and I miss her. It is killing me knowing what I have done to her but I'm going to pay for it and it's going to be a life sentence.
"I just keep thinking about what happened to her. I'm so sorry for what happened kid. I just wish we didn't have that fight, I wish it was me not her."
Then in a letter of apology she added: "There are not enough words I can say that can change the situation. I am now living with the guilt of my sister who I love more than anything and may never walk again.
"The thought destroys me every second of the day. I wish this was just a bad dream. I am so very sorry I hurt my sister. All I can say is that I cannot change what has happened as much as I would like. I can't take it back.
"I'm completely destroyed, alone with feelings of sadness, regret and guilt."
The tragedy occurred after the identical sisters had been involved in a string of bust-ups which had resulted in police being called.
In 2009 Gillian threatened to stab Louise and on another occasion tried to strangle her.
Then last November Louise herself was taken to court after attacking Gillian with a knife cutting her finger - but the pair made up. But disaster struck on April 30.
Simon Driver, prosecuting, said during the evening the two sisters had been arguing with Gillian shouting at her triplet in the communal TV room.
The sisters were asked to go back to their separate rooms which were located on the first and second floor.
But the situation worsened when Louise went into the room of another resident.
Gillian followed her a short time later and appeared to 'annoyed' as she paced up and down banging on the door before bursting into the other resident's room.
Mr Driver said: "The prosecution allege that while the two sisters and (the resident) were in the room, Gillian deliberately pushed her sister out of the second floor window in circumstances that demonstrate the intention to cause Louise serious harm.
"The prosecution allege that she deliberately propelled her sister out of the window. The dimensions were such that it could only be part of a deliberate and determined effort to push her over the safety guard, done with the intention to cause really serious harm."
Gillian admitted causing GBH with intent and was jailed for eight-and-a-half years in jail.
Judge Clement Goldstone QC told her: "Louise sustained catastrophic injuries and will never walk again. She will never have the use or have any control of her body below the ribs. You have quite simply ruined her life.
"It may be that you now truly regret what you did but you can scarcely complain about your sister's view to your letter.
"You pushed her out the window deliberately, you had no lawful excuse for doing so, you intended to cause her really serious injury.
"Even now after your letter you are continuing to minimise your role perhaps that is your way of coping."
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