Amy Winehouse's husband Blake Fielder-Civil has hit a new low by sending threatening letters to the singer's dad Mitch.

Mitch was reportedly shaken up after receiving the disturbing note but fears losing his daughter forever if he takes the matter further.

A close pal of Mitch’s told The Sun: “I could hear Mitch physically shaking when he phoned to tell me about the letter.

“He couldn’t even bring himself to read it out loud as it was just too sickening.

“But he told me that Blake described graphic scenes from a horror movie, in which Mitch is the victim.

“Part of Mitch wants to pursue this further with the police, maybe even taking out a restraining order.

“But then he is worried about it all driving a wedge between him and Amy.”

This is Blake's second twisted attempt at reaching out from prison, after he planned a drug fuelled threesome with his wife and a stranger in July.