A woman who was having an affair with a Colorado man and helped him after he beat his fiancee to death with a baseball bat was sentenced Tuesday to three years in prison. Krystal Lee, 33, acknowledged in February 2019 that she helped clean up the bloody crime scene after Patrick Frazee killed Kelsey Berreth at her townhome in Woodland Park.

The sentence was the maximum allowed under a plea deal. Without that deal, she could have faced a sentence of more than 100 years, CBS Denver reported.

"We did a deal with the devil. There's no ifs, ands, or buts about that. And I'm not proud of that. But there's no question that Kelsey wouldn't have had the sure justice today without making that deal with the devil," District Attorney Dan May said of the plea bargain.

Krystal Lee leaving the Teller County Courthouse in custody. She was sentenced to three years in prison for tampering with evidence in the murder of #KelseyBerreth. Lee cooperated with prosecutors in their case against Patrick Frazee.@CBSDenver: https://t.co/4fT2zxJL5p pic.twitter.com/1f9apNzJm8 — Shawn Chitnis (@shawnchitnis) January 28, 2020

Lee, who worked as a nurse in Idaho, told investigators she grabbed several blood-spattered items from Berreth's home to be burned, including a stuffed animal, children's building blocks and what she thought was a Bible, according to the Colorado Springs Gazette. She also acknowledged taking Berreth's phone to Idaho at Frazee's request to make it look like Berreth had left the state.

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"The most important thing I have to say is how sorry I am," Lee said through sobs during the sentencing hearing. She described having "nightmares" over her guilt. "I am sorry I did not save Kelsey."

Under her plea deal, Lee became the key witness at Frazee's trial, providing an insider's account of how he blindfolded Berreth and bludgeoned her. During the trial, prosecutors showed jurors a video of Lee leading investigators to the spot where she said Frazee burned Berreth's body.

She described Frazee putting the body in a dry water trough and lighting it on fire. At one point, she said, flames were as high as the nearby trees, so Frazee covered the blaze with what appeared to be metal roofing.

Frazee, 33, was convicted in November of first-degree murder and other charges and was sentenced to life in prison plus 156 years. His attorneys plan to appeal.

Berreth, a 29-year-old flight instructor, was last seen with her infant daughter on video from a grocery store security camera on Thanksgiving Day 2018. Her body was never found.