A woman poured petrol over her ex-lover's narrowboat on the Grand Union Canal and set it alight as he slept inside, a jury has heard.
The prosecution at St Albans Crown Court claims Kathleen Smith carried out the attack because she was angry Jeremy Brewer had finished with her.
Mr Brewer told the jury he had to be rescued by fire crews in January 2010.
Miss Smith, of Beechfield Road, Hemel Hempstead, denies arson with intent to endanger life.
Mr Brewer told the court he woke on 6 January to find the boat on fire and was trapped inside the vessel at Boxmoor.
Weeks earlier, Miss Smith had attacked him with a steam iron and told him "I will burn your boat", he said.
"I thought 'she's actually gone and done it'," he told the jury.
'Ranting and raving'
Miss Smith denies assault occasioning actual bodily harm, relating to the alleged attack with the iron in November 2009.
The court heard she began "ranting and raving" at Mr Brewer after she invited him to her home, four months after their four-year relationship ended.
He said Miss Smith then smashed an iron over his head and he had to be taken to hospital by ambulance and required 18 stitches.
Miss Smith was granted bail with conditions that she should not visit Mr Brewer and have no contact with him.
Laura Blackband, prosecuting, said Miss Smith knew Mr Brewer was on board the boat.
The court heard the melted remains of a plastic petrol can were found by firefighters and there was a strong smell of petrol around the boat.
Miss Smith elected not to give evidence.
The case continues.