Susan Smith, who is in prison for the cold-blooded murders of her two young sons in 1994, believes she has blown her chances of parole next month after being convicted of trying to capitalize on her infamy .

“She is heartbroken,” a relative told The Post. “She was so close to coming out and it seemed like it was collapsing before her eyes. She derailed it herself. She’s not happy at all.”

“She knows it’s very unlikely she’ll get out now,” the relative said. “This is a new disciplinary action, one month before her parole hearing. The parole board pays 100% attention to these things. This is really bad.”

According to the South Carolina Department of Corrections, Smith, who is serving a life sentence, was caught agreeing to provide a documentary filmmaker with contact information for friends, family and victims, including her ex-husband.

In return, the filmmaker deposited money into Smith’s account, authorities said.

The 53-year-old was charged with communicating with a victim of a crime on August 26 and sentenced earlier this month, a Department of Corrections spokesman confirmed.

The filmmaker’s name has been redacted from the report.

Inmates at the South Carolina Department of Corrections are not permitted to conduct telephone or in-person interviews. You are only allowed to write letters.

Additionally, South Carolina laws prohibit criminals from profiting from their crimes. In their conversations, Smith and the filmmaker discussed how she could get paid to film a documentary.

Smith was a 22-year-old mother when she became known for murdering her sons, 3-year-old Michael and 14-month-old Alexander. In 1994, she rolled her car into John D. Long Lake in Union County, South Carolina, while her boys were still strapped into their car seats.

Smith then falsely told police that a black man had kidnapped her and kidnapped the little ones, leading to a manhunt in which authorities went door-to-door in predominantly African-American neighborhoods.

Smith and her then-husband David appeared on the national news every day pleading for the boys’ safe return.

But nine days later, Smith finally confessed that there had been no carjacker and that she had drowned her sons in the lake.

Her alleged motive: She was having an affair with a rich man who didn’t want children. The car was pulled out of the water with the two boys still strapped into their seats.

She was convicted of murder but was spared the death penalty and instead received a life sentence with the possibility of parole after 30 years.

But Smith believes the parole hearing, set for Nov. 4, is now unlikely to be in her favor, the relative said.

Smith had a rocky road in prison. She was punished in 2000 for having sex with two guards behind bars. She has always maintained that the sex was non-consensual due to the different power dynamics.

There have also been several violations against her behind bars – including in 2010 and 2015 – for possession of narcotics or marijuana.

But for nine years, Smith has been a model prisoner – until now.

Smith lost her phone, tablet and cafeteria privileges for 90 days starting Oct. 4. Days before she lost her phone, the killer mother spoke to relatives about her plight.

“She was really, really upset,” the relative said. “And the worst part is that she knows she screwed up. That’s up to her. How could she be so stupid?”