A 14-year-old boy accused of starting a fire which killed his ex-girlfriend and her sister told the Old Bailey that he had "no intention to harm" anybody.
He said he was jealous and "frustrated" about splitting with Maleha Masud, 15, but had made "empty threats".
Maleha and Nabiha Masud, 21, died in the fire at their Lessingham Avenue home in Tooting, south London, last June.
Shihabuddin Choudhury, 20, Rasal Khan, 18, and the 14-year-old deny murder.
Mr Khan, of Earl Howe Street, Leicester; Mr Choudhury, of Coventry Road, Nottingham; and the boy also deny the attempted murder of Maleha and Nabiha's mother, Rubina, 55, and their two brothers, Junaid, 18, and 24-year-old Zain Masud.
Maleha died three days after the fire while Nabiha died a month later.
'I loved her'
The boy, who cannot be named because of his age, said he met Maleha through friends.
He said: "I loved her, I cared about her."
The Old Bailey jury heard the relationship had been kept "hush hush" from both families.
He added they had broken up several times but would make up soon after. He said he was jealous about her chatting with other boys.
"She knew a couple of boys and she tended to speak to them on MSN and I would hear these things from her friends or she would sometimes talk about them to me," he said.
"I wasn't happy with that."
After "the final break-up" he said he was "frustrated" and "really annoyed" and made "empty threats" about telling her mother about the relationship, and a day before the fire he did tell Mrs Masud.
He added: "Not at any stage was my intention to harm any of the Masud family."
The teenager said he told Mr Choudhury about the break-up.
He said: "He was telling me 'don't worry about that' because I was telling him 'I don't know what to do'.
"He then out of the blue tells me to type in on Google 'how to burn someone's house down'. He told me to type in those words.
"Me being me I typed it in without asking him 'why don't you type it in?'
"There was nothing in it and I just left it at that," he added.
Earlier the jury heard that the boy started the fire after his relationship with Maleha ended.
The trial continues.