CHICAGO (CBS) — “I would rather kill myself than hurt my children. I would rather kill myself than hurt anybody,” JoAnn Cunningham said tearfully over the phone from the McHenry County Jail.

Cunningham and her ex-boyfriend, Andrew “Drew” Freund stand accused of murdering their 5-year-old son, Andrew “AJ” Freund.

A series of exclusive conversations between Cunningham and CBS 2 Investigator Brad Edwards started with a missed call. It was from the 815 area code and included a voicemail that identified the caller as JoAnn Cunningham – an inmate at the McHenry County Jail.

The one missed call turned into phone calls and a video chat. Two letters followed.

AJ’s disappearance gripped the nation when he was reported missing by his father on April 18. The senior Freund led investigators to AJ’s body a week later on April 24. Buried in a shallow grave in a field in Woodstock, AJ was found to have died from blows to the head.

A criminal complaint alleges that Freund and Cunningham forced AJ to stand in a cold shower for an extended period of time, beat him, and sent him to bed cold and naked. This was said to have happened three days before Freund reported AJ missing.

RELATED: AJ Freund’s Parents Plead Not Guilty To Murder; Attorney Seeks Psychological Evaluation For Dad

Cunningham opened up about what she believed was AJ’s ODD, or Oppositional Defiant Disorder. ODD is defined by the Mayo Clinic as “a frequent and persistent pattern of anger, irritability, arguing, defiance or vindictiveness toward [parents] and other authority figures.”

Edwards: “Police say, on your phone… there is video of AJ lying on a bare mattress in his bedroom… and you were berating him for urinating on his bed.”

Cunningham: “Well, wouldn’t any parent?”

Edwards: “Were you using drugs when you had AJ?”

Cunningham: “When I was pregnant with him, yes.”

Edwards: “How could you be upset with AJ when you knew you were shooting up heroin when you were pregnant with him?”

Cunningham: “Heroin. It’s like the devil.”

AJ was born addicted to heroin in 2013, and was taken into the custody of the Illinois Department of Children and Family Services for 18 months before being returned to his parents. There were problems in the household years before AJ was born.

CBS 2 received access to police reports to when Cunningham and Freund were in the height of their heroin addiction:

Edwards: “Am I the only one you’ve been talking to?”

Cunningham: “Yes.”

Edwards: “Has everyone abandoned you?”

Cunningham: “Yes.”

Edwards: “Why?”

Cunningham: “Because they listened to the news.”

Long before her son died, Cunningham experienced another loss.

Edwards: “Did something terrible happen to you growing up?”

Cunningham: “Probably – my brother committed suicide.”

Soon after that, a schematic appeared – a tumultuous tangle of relationships. She divorced her husband and began a relationship with her divorce attorney, Andrew Freund – documents show they’d fight each other with knives. Her now-fiancé, Dan Nowicki, once spent six months in jail for hitting his pregnant wife.

These documents are a court record of the violence in JoAnn Cunningham’s past:

Petition For Divorce Against JoAnn Cunningham

Divorce Judgment

JoAnn Cunningham’s Order of Protection against Her Ex-Husband

JoAnn Cunningham’s Mother’s Petition For Custody Of JoAnn’s Eldest Son

Daniel Nowicki’s Indictment For Hitting Pregnant Wife

Domestic Violence Complaint Against JoAnn Cunningham’s High School Boyfriend

JoAnn Cunningham Convicted Of Misdemeanor Battery Against Drew Freund

Cunningham was seven months pregnant with Nowicki’s baby when AJ died. Cunningham believed Nowicki would be getting out of jail the day that AJ was reported missing.

Edwards: “So you went to bed, right?”

Cunningham: “Yeah.”

Edwards: “And the next morning you were going to pick up Dan from jail. And no AJ?”

Cunningham: “Yeah, yeah.”

Cunningham was making plans for Nowicki to come live with her and her ex-boyfriend, Freund. AJ and his younger brother, both Freund’s children, were also living in the house.

“I’m pregnant with someone else’s child, and he was supposed to come live with us that morning,” Cunningham said.

Nowicki was not released that day. AJ was missing. Investigators found a search for “Child CPR” on Freund’s phone – a search Freund blames on Cunningham.

“If it’s Drew, then he needs to grow some balls and he needs to tell them so everyone else isn’t suffering, you know. I’m scared,” Cunningham told Edwards, crying.

She was scared and pregnant with another man’s child – a girl who was born in mid-June.

She wrote in a letter beautiful penmanship, “I did have my daughter, Gracie Faith.”

Cunningham held her infant for two days until her daughter was taken away.

RELATED: AJ Freund Case: DCFS Timeline Raises Questions About Neglect Investigation Four Months Before Boy’s Death

Edwards: “Did you kill AJ?”

Cunningham: “No, I would never hurt my children.”

Edwards: “You say that, but some people will say you used drugs while you pregnant.”

Cunningham: “I know, and that’s something I cannot take back.”

A DCFS caseworker, investigating neglect and welts on AJ, returned AJ to the home the same day he began his on-site inquiry. AJ would be dead in four months, eventually found in a shallow grave.

“It’s always been hard for me comprehend, or understand, evil…” JoAnn wrote in a letter.

Edwards: “DCFS paints a horror show of what went on in that house. Was it a horror show, what was going on in that house in the end?”

Cunningham: “No, we were a good, loving family.”

Edwards: “JoAnn, a lot of people are just going to have a hard time believing that.”

Cunningham: “I’m sure they do, but I don’t care what they think.”

SKETCHES: See All The Sketches From This Report, By Artist Cheryl Cook

PHOTOS: Inside The Home Of AJ Freund – Images Show House Of Horrors