The attack, by South African Berlinah Wallace at her flat in Bristol in September 2015, left Dutch engineer Mark van Dongen with catastrophic injuries.
He was paralysed from the neck down, lost part of his sight and had to have his leg amputated, which 15 months later led him to travel to a euthanasia clinic in Belgium to die.
Wallace, 48, was charged with murder and throwing a corrosive substance with intent, but was only found guilty of the latter offence by a jury at Bristol Crown Court after more than 15 hours of deliberation.
Mr van Dongen’s father, Kees van Dongen, gave an emotional statement outside the court in Dutch via a translator.
“Mark was taken from us in the most difficult of circumstances,” he said.
“He was my son, a best friend and also a loving brother to Bart and his family.
“We were very proud of his studies and the results he achieved as a civil engineer in the UK. The whole process was a difficult and emotional experience.
“I’m disappointed in the outcome of this trial, there are only losers in this case. I hope that Mark can now rest in peace.”.
The court heard earlier how Wallace, a fashion student, had met the 29-year-old on a dating site for people with HIV in 2010, and had become “jealous and vindictive” after finding out he had a new girlfriend.
Before he died, Mr van Dongen told police that on the night of the attack, he had woken at 3am to hear his former lover laugh and tell him: “If I can’t have you, no one else can.”
Wallace then threw a glass of sulphuric acid over him.
Days before, she had been given a police warning for harassing Mr van Dongen’s partner, Violet Farquharson, 46.
In the his closing speech, prosecutor Adam Vaitilingam QC told the jury that Mr van Dongen had become fearful of Wallace since their relationship ended.
He said: “In her darker moments, she bought a bottle of sulphuric acid. She removed the label and she read up about attacks with sulphuric acid.
“Mr van Dongen told people that she had a violent temper and he told people he was scared of her.”
Earlier in the trial, Wallace admitted having bought the acid, but insisted that it was to clean her smelly drains.
She told the court that she thought the liquid she threw at Mr van Dongen was water, and only reached for it because the pair had become embroiled in an argument which she feared would become physical.
She claimed her five-year relationship with Mr van Dongen had seen her physically and verbally abused, and that she had depression, anxiety and PTSD.
“I didn’t mean to hurt my boy,” she claimed, as she wept in the dock.
But the court heard that Wallace was fascinated by acid attacks, had viewed more than 40 websites about the substance used in the lead-up to the attack, and had deleted 82 from her browser history.
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These included articles about the model Katie Piper, who was attacked in 2008, and graphic videos on YouTube.
The litre bottle she bought from Amazon for £17.07 had a strength of 98%, and she removed the warning label.