Jilted Catherine Jarvis 54, was so keen to marry Colin Jarvis, 55, she changed her surname to his by deed poll months ahead of their big day.
But when Colin then called off the wedding she stormed round his flat - and used a ladder to climb in over the balcony.
She set fire to the tassels of one of his chairs and left the building in Kingskerswell, Devon, to burn - causing thousands of pounds worth of damage.
Jarvis watched the fire and was arrested after Colin tipped off the police but she denied it and police later dropped the investigation.
But Colin’s persistence that she was responsible saw the case reopened and Jarvis changed her plea to guilty on the first day of a trial.
Jarvis, who used to run a wedding dress shop, had been experiencing ‘emotional turmoil’ at the time of the fire, Exeter Crown Court was told.
She admitted arson and was given a suspended jail sentence and told she had come within an inch of going to prison.
Speaking after the case Colin, a painter, said: “”We were due to be married, I called it off. That’s what triggered it all.
“We’d been together for a good two years or so, engaged for about 12 months of that.
‘’She changed her name to Jarvis because she was living with me.
“A few days later I was working away, in Surrey, and my neighbour rang me and said my house was on fire.
“I’ve lived there for 30 years, it’s my castle - I’ve done a lot of work on the house over the years.
“I set off for home and called the police because it was obvious to me Cath had started it.
“She was stood outside watching the fire. She was arrested that same day, she was in the police van when I got there.
“She denied it and the police told us they were dropping the case but I appealed the decision and I got them to look at it again.
“That time they decided there was enough and it went to court. She changed her plea right at the last minute.”
Colin says he ended the relationship when she became abusive and violent - throwing hot potatoes and ornaments at him.
He said: ‘’Before the fire, she had been out on a hen night and she got back and battered me over the head with an ornamental crab.
“She had thrown roast potatoes at me, I can’t stand physical violence like that at all. When she hit me with the crab it was over.
‘’It took me a good while to get her out, a month or so.
“I changed the locks on her but she got a locksmith out because there was a key broken off in one of the doors.
“It had been that way for years, she convinced him to change the lock so she would have a key - I didn’t realise at the time.
“I was woken up one night and she was stood in my bedroom saying, ‘I love you’ and all that. I told her to get out and said it was over.’’ The court heard she climbed a ladder to scale the outside of the house then sneaked in through a balcony door while Mr Jarvis was at work.
Once inside she set fire to the tassels of one of his chairs with a cigarette lighter and left the house in Water Lane to burn.
Fire crews put the blaze out but not before several thousand pounds worth of damage had been caused.
The court heard how the defendant had even put in a £15,000 insurance claim because most of the damaged items belonged to her.
Judge David Evans said: “There’s been an element of lying. It was a thoroughly dishonest insurance claim.
“It seems you were in some sort of emotional turmoil about recent events and you were irritated about how he behaved.
“Having called him earlier in the morning and discovering he was out at work you went around to his property and used a ladder in the backyard to access a balcony.
“You took the opportunity to sit down and play with a cigarette lighter, waving it underneath the tassels of a seat.
‘’It seems to me that what you did that day and the approach to these proceedings has been thoroughly dishonest.
“You thought you’d got away with it. It was only because of the persistence of Mr Jarvis who knew, as anyone with a reasonable frame of mind would, that you were the only candidate for starting that fire.”
“You watched as the fire service dealt with the incident. Thankfully the harm was not catastrophic as it could have been and there were no persons hurt or injured.
“There was upset and irritation which gave rise to your bizarre behaviour and your conduct throughout had been thoroughly dishonest.”
He jailed Jarvis for 21 months but suspended the sentence for two years. She was given 150 hours of unpaid work and told to pay £3,000 compensation.
Emily Pitts, mitigating, said Jarvis had not been out for revenge.
“There was a lack of consequential thinking,” she said. “Her life has now moved on.”
The defendant has one previous conviction for benefit fraud almost 20 years ago. She had previously run a wedding dress business.
Her brother had recently died in a fishing accident off Plymouth but her life was now more stable and she was in a new relationship.
“She is a dedicated and hard working person with a supportive nature but was experiencing emotional turmoil at the time”, said Ms Pitts.
“There’s been an element of burying her head in the sand.”
Colin continued after the case: “It was a good relationship, I work away a lot, I couldn’t suffer a bad relationship at all.
“I could forgive the hot potatoes but when she battered me with the crab it was a red flag - no one needs that.
“The punishment isn’t enough. If it was the other way round I’m sure I would have got a much stiffer sentence.”