As told to Ann DeGrey.

Ever since I became a single mum, I've been really reluctant to leave my two-year-old daughter with a babysitter. I just find it hard to know who to trust. I'd only just started feeling comfortable enough to go out occasionally, like a dinner with friends or a movie; nothing that meant I'd be out for too long. But even then, I never felt totally at ease leaving my daughter with strangers.

That's why I asked my 24-year-old sister Chrissy* to babysit.

She and my daughter are really close. Chrissy's the fun, silly aunt, always singing songs and mucking around. She always spoils my daughter with cute presents and loves giving her cuddles. I was grateful to have someone my daughter knew and loved. It felt safe, and I knew she'd be well looked after.

Also, Chrissy was single and living at home with our mum again after a breakup, so I figured she wasn't juggling a complicated dating life. I didn't expect any drama.

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That night, I was only going out for a few hours having drinks and dinner with an old friend I hadn't seen in years. I left snacks and explained the bedtime routine, which Chrissy already knew. I kissed my daughter goodnight and felt perfectly relaxed, leaving her with her aunty.

Everything seemed fine when I left. Chrissy had already put on 'Bluey' on the TV and my daughter was snuggled up on the couch beside her, totally happy.

A few hours later, I came home around 10:30pm. The house was very quiet. No TV, no voices, no lights on downstairs. I figured maybe Chrissy had put my daughter to bed and was reading or on her phone upstairs. But as I walked into the living room, I was surprised to see my daughter was asleep on the floor, in front of the turned-off television, still in her clothes. There was no blanket or pillow. She was just curled up like she'd fallen asleep in front of the TV.

Right away, alarm bells went off in my head. I picked her up and carried her to her room.

Once she was tucked into bed, I headed for my own bedroom to look for Chrissy and ask what had happened. But when I opened the door, I was mortified by what I saw.

There was Chrissy; completely naked in my bed, tangled up with a man I'd never seen in my life. He was also naked, and they looked shocked to see me. Like they hadn't expected me to be home so soon.

"Are you serious? In my bed when you're meant to be babysitting!" I said.

Chrissy just sighed and pulled the sheet up around her like I was the one being dramatic.

"Oh my god, it's not a big deal," she said. "She was asleep, and we were quiet. She's perfectly fine." Meanwhile, her date was getting dressed and looked embarrassed.

"She was on the floor. She should have been in her bed. You're supposed to be watching her, not hooking up with random guys in my bed."

The man apologised and said goodbye to us before grabbing his keys and literally fleeing. That's when Chrissy said, "You know I'm looking for a boyfriend. Why are you acting shocked?"

I couldn't believe what I was hearing. This wasn't just about her making a bad judgment call. It was the fact that she didn't seem to see anything wrong with it. That she brought a guy she'd met that night on Tinder into my bedroom, while my toddler daughter was left completely unsupervised. And then tried to make me feel like I was overreacting.

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I was so upset, I told her to get dressed and leave. She rolled her eyes and muttered something under her breath but eventually got up, threw on her clothes, and left.

I sat up most of the night, wide awake worrying about it all. I kept thinking about all the things that could have gone wrong. What if my daughter had woken up scared? What if she'd gotten hurt, or wandered outside? What if that man had walked into her room?

I've never asked Chrissy to babysit again.

She texted me the next day with a half-hearted apology about being sorry she crossed a line.

But she didn't really understand why I was so upset. We're still very close, but I realise I can't trust her with the most important person in my life. And honestly, that breaks my heart.

Now, I do use a babysitter; a professional, someone with references and experience. It's more expensive, but it's worth it for peace of mind.

*Names have been changed to protect privacy.

The author of the article is known to Mamamia but has chosen to remain anonymous for privacy reasons.

Feature Image: Getty. (Stock image for illustrative purposes).