A 29-year-old woman recently took to Reddit to share her story that described why a couple of tampons had ruined her absolutely happy marriage. After seven years and 2 kids together, this woman had not a single reason to believe her 30-year-old husband would ch:e:at on her. But what she discovered, later, made her wish he’d better che:a:ted after all.

The woman discovered a tampon that didn’t belong to her, inside her husband’s car.

“I (29F) have been with my husband (30M) for seven years, married for four. I’ve never had reason to suspect he was unfaithful to me or even remotely dissatisfied with our marriage—he likes to joke that we’re still living the “honeymoon phase” nearly five years and two kids in. I wouldn‘t have questioned that, or him, were it not for a surprise I found in his car last month.

When buckling our daughter into her car seat, I noticed something slotted between the cushions. I pulled it out and saw that it was a tampon. This wouldn’t have been so unusual had I not had an IUD that has stopped my period for the past year, and I didn’t even recognize the wrapper style”.

When the woman talked about it with her husband, he shrugged it off and supposed that it probably belonged to his co-worker, a married woman whose name was Fiona. Keeping in mind that he often carpools with his coworkers for lunch, the woman decided to drop it until weeks later when they were out to dinner with Fiona and her husband.

The woman couldn’t let her doubts go.

The woman said that she still had some doubts, which she wanted to put an end to. “I had sincerely wanted to believe my husband. I just couldn’t get over the way it had been tucked in the seat and how my husband had seemed not to have any regard for it whatsoever,” she explained. Her doubt brought her to the decision of faking an “emergency” during dinner, after which she asked Fiona for a tampon — and she found the match.

Once again, she had put the issue to the side, until the very same thing happened again on the morning she decided to share her story on Reddit. “This time in my sock drawer. I feel physically ill at the thought of my husband having an affair, and even more nauseated at the thought that the woman might have left these tampons out for me to find.”

After finding the second tampon, there appeared one more worrisome evidence that something was wrong.

The woman wrote, “My sister was convinced it was Fiona — either having an affair with my husband, messing with me, or both.” Then she added, “My sister and I agreed that it was too soon for cameras without any other evidence, so it was just a waiting game from there.”

She tried to look for at least some noticeable change in her husband’s behavior, but nothing happened. She was ready to call her investigation a “tampon fiasco” until her 2-year-old kid became ill. The illness itself wasn’t the problem, neither was her spouse’s decision to call off from work to take care of the baby; the problem was what the woman came home to by the end of the week.

The woman writes, “The toddler that I’d left that morning in an old PJ set was now dressed in an onesie I’d never seen before, with a tiny clip in her hair. I can’t say I have the sharpest memory, but I have a pretty good sense of what my kids wear on a day-to-day basis, and particularly what kinds of clothes they wear.”

She immediately talked to her husband. She was sure that he never made purchasing decisions for their kids’ wardrobes, and it sure wasn’t something she would have ever dressed them in, but he again denied everything.

“With our daughter in the room and my emotions all over the place, I decided to leave it,” the woman wrote. “I couldn’t make sense of it then, and it hardly seems clearer now, after I’ve driven myself half-crazy with explanations that aren’t adding up.”

The truth was discovered accidentally and left the woman in deep shock.

The woman posted an update to her story, and the truth that she revealed just turned her life upside down in a moment.

She wrote, “A Ring notification had alerted me to motion at the front door while I was at work. Half-expecting to see a delivery person, pet, or lawn care salesman for the fifteenth time, you can imagine my surprise when I saw a clip of a young woman leading my daughter into the house hand-in-hand, with my husband and other daughter close behind them. The girls were supposed to be in daycare and my husband at work. The woman, as far as I knew, was living two states away with a court order keeping her there.”

It turned out this woman was her husband’s sister. As our heroine soon realized, she was the likely source of both tampons, the onesie, and the bow. But the most disturbing thing of all was that this person had severe problems with law, and she was strongly prohibited to even approach the kids.

The woman wrote, “It wasn’t an affair at all and still, somehow, infinitely more disgusting knowing who it was and why all of this had been happening. Apparently my SIL, fresh off another stint in rehab, had wanted to reconnect and make amends with people she’d hurt, and my husband was high on that list. My husband didn’t want me to know or, worse, try and keep ‘her family’ (our children) away from her, so they’d been meeting in secret—often at our house when I was at work.

They would enter through the garage, in my husband’s car, so the Ring camera at the front door wouldn’t tip me off. She spent the night on a weekend I had been on a business trip and slept in our bed. She babysat our girls on a night my husband told me he had dropped them off at his parents’. She bought the girls clothes and dressed my youngest in the onesie and bow that my husband had promised on his life, I had dressed her in myself.”

Now, the woman is going to follow one of the commenters’ advice: “Call the cops and a lawyer.” And she will never ever be able to trust her husband again.