Amy Winehouse's husband fears she'll die without him by her side

Amy Winehouse's incarcerated husband Blake Fielder-Civil has told a pal he's worried his troubled wife will die without him by her side.

Fielder-Civil -- who's locked up in London's Pentonville Prison accused of assault and conspiring to pervert the course of justice -- also said he would leave Amy if she didn't stop taking drugs and that he was upset the singer had missed a string of prison visits to see him in jail, where he is on remand.

"He doesn't want to go back to Amy because she's doing drugs. People might see it as scandalous, but it has to happen for him to be OK," the pal said.

"If Blake was released tomorrow I think they'd go their separate ways."

Blake is also angered that Amy books visits to see him but fails to show.

"It really upsets him when she lets him down. She books visits and doesn't turn up so no one else can go," the pal added.

Fielder-Civil's thoughts were made public after Sarah Thomas, who Fielder-Civil affectionately calls Baby Bear, handed over the letters he had written to her from prison to British magazine Grazia.

In one letter shown, Fielder-Civil writes: "How much is my wife trying to do my head in!? Can't help feeling I'm going to see a photo of her snogging some junkie soon! She needs to remember she's married to someone in prison."

Thomas -- who has been Blake's closest confidante since his incarceration last year -- also revealed that the drug addled couple once had plans to have children, saying: "They've talked about having kids, and Amy is actually very maternal. She likes taking care of people, and does wifely things like making pillowcases out of tablecloths."