'I had a threesome with my best friend and her boyfriend. But I crossed the line after she fell asleep.'

It all started with a drinking game. Truth or dare. 

"Truth!" my best friend, Emma, said when it was her turn. 

"If you and Dan had to have a threesome with someone in this room, who would it be?"

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Emma grinned at Dan, her boyfriend of three years, and they both answered at the same time. 

"Holly!"

Everyone turned to look at me and I felt my face growing hot. 

"Yeah, so how about it, Hol?" Dan joked - and the entire room erupted with laughter. 

Up until that moment, I'd never considered the idea of a threesome with two of my closest friends. But it was clear from their reactions that they'd had a conversation about it. 

As the night wore on and the drinks continued to flow, I realised I couldn't stop thinking about it. 

After the party wound down, it ended up being just the three of us left - and the inevitable happened. We ended up in the bedroom. 

Emma kissed me, slowly slipping my dress off my shoulders, cupping my breasts in her hands, while Dan watched. Then it was his turn to kiss me. He put his lips on mine and immediately, I felt a spark.

I'd never even entertained the idea of having sexual chemistry with my best friend's boyfriend. But as his tongue entered my mouth and he pressed his body against mine, it was undeniable.

Shaken, I went back to Emma, suddenly feeling... vulnerable. Dan watched, stroking himself, as I bent my head to lick and suck on her nipples. 

Soon all three of us were naked and in the bed. Dan had sex with Emma while I watched. Then he asked her if he could f*** me as well. 

She nodded and I gasped as he thrust inside me. I came in minutes, harder than I ever had in my life. 

When it was all over, Dan and Emma fell asleep in each other's arms and suddenly, I felt like the spare part that I was. I grabbed a blanket and went to lie on the couch. 

At some point during the night, I heard the door creak and Dan appeared, stark naked and hard in the lounge room. 

"Where's Emma?" I whispered, feeling my clit throb and my nipples harden. 

"Asleep," he said.

Without a word, I grabbed his hand and pulled him on top of me. I told myself it was fine. That I'd f***ed him just a few hours earlier with Emma's full permission. But I knew deep down, it was wrong. 

It couldn't help myself though. We f***ed hard and frantically, both of us exploding within minutes. 

I was still catching my breath when Dan tiptoed back to the bedroom.

There was never any awkwardness between the three of us afterwards. We even had breakfast together the next morning, and the next time we hung out, it was exactly as before.

But every now and then, when we're together, Dan will catch my eye across the room and I'll feel the undeniable spark I felt the first time he kissed me.

I know we're both guilty of crossing the line. But that will remain our little secret.

Feature image: Getty. The photo used is a stock image. The author of this article is known to Mamamia and has chosen to remain anonymous for privacy reasons.