"I'm not going to make anything about this because I'm not sure you understood it or anyone explained it to you," DeFino-Nastasi added.
"It's called a gag order," the judge said, and told Windslowe not to write again.
Parts of Windslowe's letters to the newspaper were published Friday. Windslowe, 42, complained that she has been held on $750,000 bail for 28 months and her trial on a charge of third-degree murder is not scheduled until Feb. 17.
She also wrote that she was sorry about the Feb. 11, 2011, death of exotic dancer Claudia Aderotimi, 20, allegedly after silicone injections in her buttocks, and wanted to plead guilty.
Windslowe added that she was only willing to plead guilty to involuntary manslaughter. If the District Attorney's Office insists on the more serious count of third-degree murder, she wrote, she wants a jury trial. Third-degree murder carries a prison term of 20 to 40 years; involuntary manslaughter, 21/2 to 5 years.
Windslowe, dressed in a pink suit, her hair pulled back into a ponytail held by a matching pink ribbon, said she understood DeFino-Nastasi's warning.
The judge said anything Windslowe says publicly can be used against her at trial even if she thinks she is helping herself.
DeFino-Nastasi said Windslowe's missives could also make it harder to select an impartial jury.
"If we have to have a venue change out to one of the counties, I don't think you'd like that," she added.
DeFino-Nastasi set Aug. 14 for a hearing on several pretrial motions.
Defense attorney David Rudenstein said he wants to use evidence to mitigate the possibility that jurors would find Windslowe was motivated by malice in her silicone-injection sideline. That could support an involuntary-manslaughter verdict.
Assistant District Attorney Bridget Kirn said she wants to use "evidence of prior bad acts," which could support a third-degree murder verdict.
Windslowe allegedly made a profitable living illegally injecting women with silicone though she had no medical license or training. Aderotimi died after flying to Philadelphia from London to get the injection in an airport hotel.
Windslowe was arrested in February 2012 after another woman complained of twice being hospitalized after attending a "pumping party" in East Germantown where Windslowe allegedly injected her and other women.
Silicone injections for buttocks enhancement are illegal in the United States.
One motion the judge said she would not grant is Windslowe's release on electronically monitored house arrest pending trial.
"I do think she is a risk of flight," the judge added, "and this is the kind of behavior she could engage in even on house arrest."