'I saw what the matron of honour did at the hens party. So I told the bride and got her sacked.'

As told to Ann DeGrey.

Sienna* and I had been friends for years, ever since we met at university. She was the kind of friend who made everything fun – she had a huge personality and loved a laugh. She always had some kind of drama in her life but our friendship had survived all kinds of ups and downs.

So, when Helena*, our other close friend, asked us both to be part of her bridal party, I was beyond excited. Sienna was chosen to be the matron of honour, which made sense because she was married and had been a huge support to Helena over the years. I was happy just to be included as a bridesmaid. The three of us had shared so much, and I couldn't wait to stand by Helena's side on her big day.

Everything was going smoothly until the hen's night. Helena had planned this fun, light-hearted evening with drinks, games, and a male stripper. It wasn't exactly my cup of tea, but I knew the other girls were excited, and I wanted to make sure Helena had the best time. That night started off with a lot of laughs, but things took a turn for the worse.

Watch: Unsolicited advice may be one of the many signs of a toxic friendship. Post continues after video.

The stripper arrived, and I noticed Sienna getting a bit more involved than the rest of us. At first, it was harmless flirting. I shrugged it off, thinking she was just having fun. After all, we were all there to let loose and celebrate Helena's last few days of being single. But as the night went on, Sienna's flirting turned into something more. She was getting touchy with the stripper, whispering in his ear, and I saw her hand lingering on his thigh a lot longer than it should have. I forced myself to shut my mouth though, because it was supposed to be a fun night, and maybe I was overreacting.

But then, the real shock came later that night. After the performance, while everyone was still drinking and chatting, I noticed Sienna leaving with the stripper. I couldn't believe it and I wasn't sure what to do.

I wasn't sure what to do with the information, but deep down, I knew I had to tell Helena. She deserved to know, even if it was going to be upset.

The next day, I spoke to Sienna who told me she'd had a "one nightery" with the stripper and made me promise not to tell her husband. Well, I didn't tell her husband but I told Helena who was horrified. Helena's husband-to-be was best friends with Sienna's husband so this was a big deal.

She thanked me for telling her, but I could hear the shock in her voice. She said she needed to process it, and we hung up. Later that day, Helena called Sienna, and things blew up. Helena told her that she was no longer welcome at the wedding and that she was sacked as matron of honour. I wasn't there for that conversation, but I can only imagine how it went. Sienna must have been devastated — and angry.

Word got around quickly, and it wasn't long before I received a message from Sienna. It wasn't the kind of message I'd ever expected to get from her. She was furious. She called me a "dirty dibber dobber," someone who couldn't keep her mouth shut. She said I'd ruined everything, that it wasn't my place to meddle in her business, and that she would never forgive me. I tried to explain that I hadn't meant to hurt anyone, but she didn't want to hear it.

"Why couldn't you just keep your mouth shut? You've destroyed everything," Sienna said. I told her that I thought I was doing the right thing and I wanted to protect Helena.

"Protect her from what? Me?" asked Sienna. That was the last conversation I ever had with her.

After that, our friendship was over. We didn't speak again, and to this day, Sienna hasn't forgiven me. Helena went ahead with her wedding, but it wasn't the same without Sienna by her side. The whole thing left a bitter taste in my mouth. I had only meant to do the right thing, but in the end, none of us came out unscathed. Helena and I stayed friends, but our once-close group had fallen apart.

I still think about Sienna from time to time. I wonder if I should have handled things differently or if telling Helena had been the right choice. Maybe I could have found a way to talk to Sienna privately, to help her make things right without tearing everything apart. But at the time, it felt like there was no other option. I just couldn't keep what I'd seen to myself.

In the end, doing what I thought was right cost me a friendship that I'd treasured for years. And even now, I'm not sure if I made the right call.

*Names have been changed due to privacy.

The author of this story is known to Mamamia and remained anonymous for privacy.

Read these stories next:

Feature image: Getty.