Zak Rodda, 32, started the blaze in the bedroom of Charlene Clarke’s home then sent a series of chilling messages to her from a pub.
The fire reduced four houses to “shells”, causing more than £100,000 damage. Charlene’s two cats also died.
Rodda was jailed for six years after admitting arson and reckless endangerment to life.
Care-home boss Charlene has spoken up for the first time after her insurance company refused to pay out because Rodda is the policy holder, leaving her and daughter Larenza, nine, homeless.
The 33-year-old said: “He’s ruined my life. We have no home, my little girl is terrified and I’ve had to move back in with my mum.
“I’ve been off work with anxiety, I can’t quite believe he would do this to us.
“Even the judge said he wished he could give him life.” The couple had been together for 15 years.
Charlene added: “We’re so lucky no-one was seriously hurt. It just shows you never really do know someone. He ended up being a psycho.”
The arson attack came after Rodda had been convicted of driving with no insurance and taking a vehicle without consent, in January, for breaking into Charlene’s house and stealing her car.
Charlene allowed him to stay in the family home as she didn’t want to disrupt their daughter’s routine.
But in March Rodda packed up and left her for another woman, leaving her “heartbroken”.
When he went back to her weeks later she stood her ground, refusing to rekindle their volatile relationship.
But Charlene claims controlling Rodda said he wouldn’t leave the family home.
Before and after he started the fire, he sent a series of threatening text messages to Charlene with one saying: “Look see the light, I warned you’’ and ‘‘There she goes, goodbye”.
She said: “He’d been a bit up and down for years but I never thought for one second he’d do something like this.
“When he left me for another woman I’d really had enough and after 15 years I told him I was done.
“But after his aunt died he invited me to a family gathering in her memory and I wanted to support him so I went along – but only after he’d promised not to kick off.
“After a few hours he wanted me to leave with him but I refused. He sent me some threatening texts after that and then next thing I know I’m being told my house is on fire.
“It was a really windy day so the fire spread fast, I feel so guilty for all our poor neighbours. A few of them didn’t have home insurance so they have lost everything.”
Rodda’s barrister Brian FitzHerbert told the court that he made immediate attempts to put out the fire and had called the emergency services himself.
He told Truro Crown Court earlier this month: “There was an element of bad luck in that high winds caused the fire to spread more quickly than Mr Rodda would have anticipated.
“Two weeks before the incident he sought help from his GP for depression and the early stages of suicidal thoughts. Days before the fire his aunt died suddenly, someone he was very close to.”
Charlene, from Illogan near Redruth, Cornwall, said: “I’m so grateful for all the support from my neighbours which I feel I don’t deserve, and to my family.
‘’I thought getting cheated on was the worse thing in the world but it turns out I was wrong. He set fire to the house and let our cats die painful deaths. I can never forgive him for what he’s done.”