His elaborate marriage proposal lacked a ring of truth — especially when his mistress interrupted it.

Tiffany Lyn‘s stomach was aflutter with butterflies as she held her boyfriend CJ’s phone in her hands.

The head-over-heels-in-love New Yorker was recording her sweetie as he voluntarily participated in “Fear Factor Live” — a competition in which daredevils test their strengths — in front of a live audience at Universal Studios in Orlando, Fla., in July 2013. 

Midway through the show, he publicly asked Lyn: “Will you marry me?”

But her giddy excitement turned to abject devastation when a text message suddenly appeared on CJ’s phone, reading: “Fine, go ahead and marry her. She’s the safe choice for you,” followed by a less than flattering critique of his most recent sexual performance. 

Lyn ultimately learned that the author of the shady missive was a woman whom CJ had been secretly sleeping with throughout their two-year romance. 

“The best moment of my life turned into the worst moment of my life,” Lyn, now 42, a digital marketer in midtown told The Post. 

“It’s taken me 10 years and about $10,000 in therapy to finally be able to talk about it,” Lyn told The Post. “I’m telling my story now because I want to help others who might find themselves in a similar situation.”

Unfortunately, the Manhattanite’s miserable discovery isn’t all that uncommon. 

In fact, she’s just one of the many broken-hearted honeys — including A-listers such as Shakira, Nia Long and Khloe Kardashian — to learn of a lover’s infidelity by eye-popping happenstance. 

Influencer Mia Dio, 22, uncovered the ugly truth of her partner’s extra-relational misdeeds via AI software in August. 

And at the dawn of November, Katherine, an Idaho mother of twin toddlers, sent jaws to the floor after revealing she’d caught her now ex-husband carrying out an affair with her own mother. 

“I didn’t want to believe that the two people I trusted the most in this whole world could betray me like that,” she lamented to more than 15 million TikTok sympathizers.

Lyn was, too, was in total disbelief upon learning of CJ’s wrongdoings. 

“I just smiled,” Lyn recalled to The Post, noting that no one in the crowd of onlookers at the theme park knew she was the object of the oaf’s overture. 

“I’m really good at masking my trauma without making a scene,” said admitted, “so I didn’t say anything at all.”

Rather than explode on her cheating Prince Charming, Lyn accepted his diamond engagement ring — a two carat, round cut solitaire — and calmly addressed his unfaithfulness. 

Without hesitation, a seeming contrite CJ confessed his sins and begged for forgiveness, which Lyn initially granted due to her unyielding love for the hunk. 

But after two months of trying to make it work, the troubled twosome called it quits. 

“I just could regain that trust,” she said. “Every time I looked at the ring on my hand it felt tainted.”

Lyn returned the rock and permanently discontinued contact with CJ. She did however learn that the deceiver has suffered through a series of failed relationships, including a divorce, since their breakup.  

“He’s a certified narcissist,” said Lyn, “I hope other women protect themselves against jerks like him.