Joyce Mitchell, 51, was charged with promoting prison contraband, a felony, and criminal facilitation, a misdemeanor.
Mitchell faces a prison sentence ranging from two and a third years to seven years. She will be sentenced in September.
In statements she gave police in early June, Mitchell detailed how she bought and delivered tools to the two men so they could break out of prison. After the jailbreak, Mitchell was supposed to bring them a Jeep, a gun, a GPS, money and other materials to the men, but she backed out.
Mitchell also detailed how she was supposed to give her husband two pills to knock him out, and the plan called for one of the escaped inmates to later kill her husband, Mitchell said in her statements to police.
CNN obtained copies of her statements
under the Freedom of Information Act.
Not enough evidence for murder conspiracy
In court on Tuesday, however, Mitchell was about to become an inmate herself: She dabbed tears from behind her eyeglasses.
Mitchell's lawyer, Stephen Johnston, described his client as anxious, depressed and remorseful.
"She got in over her head into something she never should have started, but she did and she is paying the price now and she realizes she made a horrible mistake," he said.
Clinton County District Attorney Andrew Wylie told reporters that he couldn't use her word alone to convict Mitchell on a charge of conspiracy to murder her husband. The inmates reportedly planned to kill her husband after the breakout.
The inmate who was recaptured, David Sweat, did not corroborate the notion that the inmates planned to kill Lyle Mitchell, Wylie said. "Because of the facts that we had before us, to prove such a charge beyond a reasonable doubt would have been extremely difficult," the prosecutor said.
Johnston denied Mitchell's involvement in a plot to kill Lyle Mitchell.
And Lyle Mitchell himself has said he still loves his wife.
"He is still hopeful that he will have a life with her," his attorney Peter Dumas said Tuesday.
Mitchell reveals jailbreak plan
Authorities said Mitchell, a tailor at the Clinton Correctional Facility
, provided inmates Richard Matt and Sweat with tools they used to cut through cell walls for their escape from the prison in Dannemora, New York.
The escape was discovered on June 6. A massive manhunt ended in late June after law enforcement officers fatally shot Matt and recaptured Sweat.
Last April, Mitchell bought a screwdriver bit for Matt and then two hacksaw blades from Walmart the next month, bringing the blades to work in her bag, according to Mitchell's statements to authorities.
"After a couple of days, he told me he and Inmate Sweat had cut the holes and were going down in the pipes," Mitchell said in her statements to police. "I was already bringing stuff in to him, and didn't really feel I could stop. I have known about them cutting the hole in the wall for about three or four weeks."
A plan to kill 'the glitch'
Each time Matt asked for tool, Mitchell bought it at a store, she said.
"I was aware these tools were being used by Inmate Matt and Inmate Sweat to escape," Mitchell said in her statements.
"The day they were supposed to escape, I was supposed to give my husband, Lyle, two pills. These pills were intended to knock Lyle out so I could leave the house," Mitchell said in her statements.
Mitchell was then supposed to rendezvous at midnight with the two escapees in Dannemora, but she couldn't do it, she said.
"I was to drive my Jeep and bring my cell phone, GPS, clothes, a gun, tents, sleeping bags, hatchet, fishing poles, and money from a package I never picked up," Mitchell said in her statements.
"After I picked them up, the plan was to drive to my home and Inmate Matt was going to kill 'the glitch.' Inmate Matt referred to Lyle as 'the glitch.' After Inmate Matt killed Lyle, we were going to drive somewhere. I can't remember where we were going to go, but I know I was told it was around six-seven hours away."
The plan ultimately called for Mitchell and Sweat to be together, with Matt going off by himself, she said.
"On June 5, 2015, Inmate Matt told me it was the day he and Inmate Sweat were breaking out of the facility. I know I had agreed to help them escape and run away with them, but I panicked and couldn't follow through with the rest of the plan. I really do love my husband and he's the reason I didn't meet Inmate Matt and Inmate Sweat," Mitchell said in her statements.
"I didn't want anything to happen to Lyle and I couldn't imagine being without him. I believe I helped Inmate Matt and Inmate Sweat escape because I was caught up in the fantasy. I enjoyed the attention, the feeling both of them gave me, and the thought of a different life," Mitchell said in the documents.
Plea deal 'in the interest of justice'
Mitchell admitted that with the help of another prison employee, she smuggled hacksaw blades by hiding them in frozen hamburger meat, a law enforcement official told CNN last month.
Mitchell faced up to eight years behind bars if tried and convicted, authorities said.
Officials said Matt and Sweat had originally planned to come out of a manhole and meet Mitchell, who would drive them away. But Mitchell didn't show up, officials said.
Despite their botched getaway plan, Sweat and Matt managed to elude authorities for about three weeks. They fled through the woods of upstate New York, breaking into a cabin and collecting supplies.
Though Mitchell was said to have had a relationship with the inmates, Sweat did not confirm that he had sex with her, according to Wylie.
"He did not confirm that whatsoever," Wylie said.
In her voluntary statements to authorities, Mitchell stated she had a sexual relationship with Matt.
She also gave notes "of a sexual nature" to Matt to give to Sweat, "but I never had any sexual contact with Inmate Sweat, only Inmate Matt," Mitchell said in one statement to authorities.
Mitchell potentially faced additional charges -- including allegations of sexual conduct with one of the inmates, and allegations that there was a conspiracy to have her husband killed -- but Tuesday's plea deal precludes that, Wylie said.
"I made a determination it was in the interest of justice" to proceed with the plea on the two counts, Wylie said.
Mitchell, however, could still be charged with other counts if an inspector general's investigation turns up any new crimes, the prosecutor said.
New York State Inspector General Catherine Leahy Scott said in a statement that Mitchell's guilty plea made "clear her culpability in the systemic breakdown that led to the escape of two cold-blooded killers."
The plea deal includes Mitchell's continued cooperation in the broader investigation of the prison.
"Nothing short of her full cooperation will be tolerated, and I am confident that when she fulfills this obligation, I will provide a thorough and complete accounting of all the factors contributing to this elaborate breakout, with an eye toward ensuring this never happens again," the inspector general's statement said.
Grand jury to investigate
Plea negotiations with the lawyer for another prison employee, Gene Palmer
, have failed and his case will be presented to a grand jury, Wylie said. Palmer is accused of taking meat that concealed the hacksaw blades to Sweat and Matt, who subsequently escaped.
Palmer was a guard on the honor block where Matt and Sweat were housed. His former attorney has said the guard was unaware of the meat's contents when he was asked to get it to Matt.
After Sweat's capture, the inmate told police that he and Matt conducted a practice run of their prison break the night before they disappeared, a state official said.
Three members of Clinton Correctional Facility's executive team, along with nine security staff employees, have been placed on paid administrative leave as part of the review of the escape, according to the New York State Department of Corrections and Community Supervision.
Superintendent Steven Racette and Deputy Superintendent Stephen Brown are among the executives on leave, a state official told CNN. The other is First Deputy Superintendent Donald Quinn, according to a source familiar with the investigation.
The FBI is investigating possible broader corruption at the prison
, law enforcement officials briefed on the case told CNN. Agents are looking into whether drug trafficking or other criminal behavior among employees and inmates took place, officials said.
Some employees who have been questioned told investigators that there was heroin use among prisoners and an alleged drug trade involving employees, the officials said.