On her release, she was taken into immigration detention and is awaiting a decision by Australian ministers.
Webb, who left the UK when she was two, fears she and her children would end up living on the streets if deported.
Under Australian law, visas can be revoked when someone has spent more than a year in jail.
Webb, 30, has not been back to the UK since her mother, father and elder sister first travelled to Australia, in 1988, from Stoke-on-Trent.
She said: “If I end up in the UK, I’d have no housing, no family, no friends. I could not take the children – I could not be that selfish. I would be living on the streets with the poor little buggers.”
Webb, who never became an Australian citizen or naturalised, said: “Had I known this could happen, I would have got citizenship.
“If the minister says I can’t stay, there’s nothing else I can do. I’ll have to pack my bags. They will take me to the airport. And that’s it.”
Webb, from Geelong in Victoria, said she found out she faced deportation in March, three days before she was due for parole.
“This is the cruellest thing anyone could ever do,” she said, adding that her prescription for anti-depressants had been doubled to help her cope.
Webb has an extensive criminal history, including a conviction for killing her stepfather. She was sentenced to a good-behaviour bond after the court heard he had been abusive over an extended period.
“I know I have done a lot of bad things – they’ve been mostly due to drug addiction,” she said, adding that she has undergone recovery and rehabilitation programmes.
“I’m not a bad person. I made wrong choices. I want a quiet life with me and my children. I want to keep my family together.”
Her eldest, nine, currently lives with his father in Perth. While in prison, her six-year-old twins and five-year-old son are being cared for by their paternal grandmother, and her one-year-old baby girl is with Webb’s mother.
Her late husband, father to her four youngest, was killed in a motorcycling accident last year.
While in detention, she is able to see her baby once a week, but has not seen her other children and describes the conditions there as worse than prison.
“It’s so, so hard. I just want to be a mother to my children. Their dad was killed – I am all they have got.”
In December 2014, the Migration Act 1958 was amended to introduce new mandatory powers to cancel visas of “non citizens” who have been sentenced to 12 months or more in prison. These “non-citizens” can seek to have this revoked.
In Webb’s case, ministers are likely to take into account the seriousness of the offence and the best interests of the children in deciding whether she can stay.
Australia’s immigration department said it would not comment on the specific details of this case.
Between December 2014, when the law changed, and the end of March this year, Australia deported 441 people whose visas were cancelled, the department said.