Heather Elvis was already the target of vicious text messages after a tryst with a 38-year-old married father was exposed by his wife.

But when the 20-year-old South Carolina woman vanished and her abandoned car was discovered Dec. 19, 2013, near a boat landing in Myrtle Beach, the smear campaign against her only intensified.

Her body was never found, but cellphone records led police to the man with whom Elvis had an affair, Sidney Moorer, and his wife, Tammy. With the investigation focused on them, the couple took to social media to attack the young woman, portraying her as an obsessed and unstable homewrecker, according to prosecutors.

“Well Sidney cheated on me in the months of Sept/Oct with a psycho whore who has since went missing,” Tammy wrote in a Facebook post referenced in court.

For his part, Sidney claimed his one-time lover pursued and stalked him even though his wife went to great lengths keep her away from him — monitoring his phone use and even handcuffing him to the bed at night, according to police records.

Both the Moorers were charged in connection with Elvis’ disappearance, but nearly five years later, the courts still haven’t determined if they’re responsible.

The couple initially was charged with murder and kidnapping in 2014, only for the murder charges to be dropped two years later. Sidney was tried on the kidnapping charge in 2017, but a mistrial was declared when the jurors couldn’t deliver a unanimous decision. His case was not retried and a future date has not been set.

Both Tammy and Sidney were indicted for conspiracy of kidnapping in 2017. The most recent indictments do not name Elvis as the victim, but they say that the Moorers conspired on the day that Elvis disappeared.

Sidney was sentenced to prison last year for obstruction of justice, bringing a modicum of justice to the Elvis family in what has been a complicated, drawn-out legal process.

Now, following years of legal setbacks, Tammy will go on trial on the kidnapping charges for the first time, with testimony set to begin Tuesday in the Horry County Courthouse.

“It’s a rollercoaster of emotions and it has been for the past five years,” Heather’s mother, Debbi Elvis, told The Post. “It actually feels worse now. Before, we were more in a fog.”

While the legal drama has played out, the Moorer couple has continued to disparage the missing woman as well as those who have stood by her, according to court records and loved ones.

“It’s a very volatile case, volatile to the point of both sides receiving violence,” Debbi said.

‘An angel and a devil fell in love’

Prior to her disappearance, Elvis worked at a local pub named Tilted Kilt, where she first encountered Sidney, who performed repair work at the Celtic-themed bar known for the lively atmosphere and skimpy outfits that servers wore.

Soon enough, the pair started talking and Elvis gushed about him to her co-workers, according to testimony from the 2017 trial. Colleagues recalled that Sidney would drop by off the clock to bring her coffee and bagels.

During his obstruction of justice trial, Sidney claimed their brief affair began in September 2013. Sidney allegedly talked about moving to Florida and Elvis joining his family as a nanny for his children, according to her friends.

Elvis, however, may have had reservations about their relationship, which she appeared to allude to on social media. “Once upon a time, an angel and a devil fell in love. It did not end well,” she wrote on Twitter in mid-September 2013.

Their relationship came to an abrupt end weeks later in October when, according to Sidney, his wife learned of their car rendezvous.

Elvis’ roommate and close friend, Brianna “Bree” Warrelmann, said once Tammy discovered the affair, she “exploded” and barraged her husband’s lover with calls and texts, going as far as to send a photo of her husband having sex with Elvis, according to court testimony and media interviews.

“Tammy called Heather and said, ‘You’re going to end it with my husband,’ and so she put Sidney on the phone, sat there while Sidney and Heather talked,” Warrelmann told Crime Watch Daily. “They ended things on the phone but Sidney made comments to Heather and said, ‘You were nothing to me, you were just someone who spread your legs’ and basically tore Heather apart as a human being, and who she was as a person and made her feel horrible about herself.”

Phone records revealed the harassment continued from the then-41-year-old woman, according to court records.

“Hey sweetie ready to meet the Mrs.,” Tammy texted to Elvis in a Nov. 1 message.

The relentless messages prompted the 20-year-old to respond in a message saying, “I think you are a little obsessed with me. I’m nobody you need to worry about anymore.”

‘You’re finally moving on with your life’

Elvis was despondent over the breakup, according to acquaintances, but she appeared to have a new lease on life as the holidays approached. She recently had been hired as a makeup artist and planned to start attending church with her roommate, Bree.

On Dec. 17, Elvis went on a first date with a man named Stephen Schiraldi and they drove around neighborhoods looking at Christmas lights. The 20-year-old sent her father a photo of her driving her date’s stick-shift vehicle with the caption, “Just learned to drive stick. I’m a pro.”

Schiraldi said he dropped her off at her apartment around 1:15 a.m. and they made plans to see each other again.

Excited about the date, Elvis called her roommate to recap the night. But later, around 1:44 a.m., she called Bree again, upset about a troubling phone call from Sidney.

“He said that he left his wife that he missed her and wanted to see her and be with her,” Bree testified at Sidney’s trial. “I got angry and said don’t do it. You’re finally moving on with your life. You’re happy again. You’re yourself again.”

Elvis allegedly agreed on the phone with Bree that she would sleep on it before deciding how to respond to him.

But around 2:30 a.m., Elvis left her house and drove to Longbeard’s Bar and Grill in Carolina Forest, where she was until about 3 a.m., attempting to contact Sidney several times between 2:29 and 3:16 a.m., according to prosecutors. They claim she called Sidney on his phone a final time at 3:19 a.m. and spoke with him for more than four minutes.

She then reportedly drove to Peachtree Boat Landing, prosecutors say, where her car was discovered the following day.

Surveillance footage showed a vehicle that matched the description of Sidney’s going that evening from the Moorer home to the boat landing and back.

Sidney told investigators that he had no contact that night with Elvis and was with his wife, who had handcuffed him to the bed, as per their agreement to win back her trust.

Authorities, however, placed Sidney via surveillance cameras at a pay phone that made a call to Elvis around 1:35 a.m. Dec. 18. He then claimed that he was telling her to stop contacting him.

Other footage from the same night showed him purchasing a pregnancy test, which he told investigators was for his wife, even though Elvis texted him about gaining weight and friends testified she was concerned she was pregnant.

It wasn’t until Feb. 21 — more than two months after Elvis’ disappearance — that the Moorer couple was taken into custody and charged with indecent exposure and obstruction of justice. (The indecent exposure charges against the pair were later dismissed, along with Tammy’s obstruction of justice charge.)

Meanwhile, the couple’s smears against Elvis littered social media pages and message boards, which rallied behind them when they were initially charged in 2014.

With years of complications in the proceedings, including the kidnapping trial against Sidney that ended with a hung jury, there has been plenty of speculation but little resolution in the case.

“The very worse was when they had the hung jury,” Debbi told The Post about the 2016 kidnapping trial. “It was like they were walking out on my daughter and I can’t do anything about it.”

In the intervening years, the Elvis family has fought to wrestle back their daughter’s identity from the Moorers, defense lawyers and online trolls.

“People were kicking someone who was down,” Debbi said about the online harassment. “They were talking about someone who was gone.”

When the court hears Tammy’s case this week, the Elvis family is hopeful that they’ll decide not only whether she is guilty in the disappearance, but put to rest the “horrific depiction” of their daughter.

“Our main thing we’re hoping for is that there is justice in this case and that there is punishment enough for both of the parties,” Debbi said.