A man accused of murdering his ex-girlfriend’s new partner in a jealous rage says he killed him in self-defence after fearing for his life.

Kaydon Prior, 23, told a jury he feared for his life when Harrison Tomkins came at him with a knife.

They fought after Prior let himself into 21-year-old Alicia Parrin’s flat and found her in bed with Harrison Tomkins, he told Chichester Crown Court.

He admits stabbing the leisure centre lifeguard and amateur boxer but says he did so in self-defence.

Prior told the jury the pair traded punches before he was knocked on his back on the bed.

He then said: “He was bigger than me, he was stronger than me and I was vulnerable.

“Then, yeah the knife, the knife was in Harrison’s hand.

“I’ve put my hand up against his arm and tried to grab the blade.

“I’ve kicked him and the knife ended up on the floor.

“As soon as the knife was dropped, we are still grappling and punching and we both ended up reaching for the knife and I managed to get it first because it’s closer to me.

“I picked it up and I swung it at him, I stabbed him.

“I felt, he gets that knife before me, I’m not going to make it out of this room, not without at least being seriously hurt.”

Prior then told the court he froze in shock after Mr Tompkins fell onto the bed.

He added that he was “crying his eyes out” while calling his mum after leaving the flat.

Mr Tompkins was stabbed ten times with a 16cm hunting knife.

Prior also told a jury he bought laughing gas about three hours before stabbing Mr Tompkins.

He denies murdering the 25-year-old lifeguard who had spent the night with Ms Parrin at her flat in Ifield near Crawley.

Prior told the jury he bought "Nox", slang for nitrous oxide, in Crawley after coming back from a night out in West London.

Charlotte Newell KC, defending Prior, asked him if he had rushed back from London in a rage after hearing Ms Parrin was with another man.

He denied this as well as wanting to “kill her or any man she was with”.

He also denied that laughing gas makes you want to kill.

A jury at Chichester Crown Court heard a mutual friend of Prior sent Jason Curtis, 22, a snapchat picture of Ms Parrin kissing another man.

Curtis is also co-accused of murder.

Prior and Curtis deny murdering Tomkins at the flat in Crawley on August 13 last year.

Prior also denies beating Ms Parrin and carrying an offensive weapon.

The trial at Chichester Crown Court continues.