"When they broke up, I told my friend exactly what I'd thought of her ex. Now they're back together."

Image: The ‘Girls’ gang didn’t really like Marnie’s boyfriend Desi. (HBO)

“Are you free tonight? Sam* and I just broke up.”

It sounds awful, but I was so happy when I got this message from my best friend Kate*. Okay, maybe not ‘happy’ — breakups suck and she was clearly distressed — so let’s go with relieved.

Context: I had never liked her boyfriend Sam, which is kind of uncomfortable because they’d been dating for almost two years and the three of us had spent a lot of time together. But I’d just never warmed to him.

Before I was actually introduced to Sam, Kate had been talking for months about this interesting, handsome, witty guy she’d met through work. Their agencies had collaborated on some project and the two of them kept in touch via email and then Facebook when it came to an end. Eventually, they started going out for drinks and you can guess what happened next.

I tried to like Sam. I really, really did.

The first time I met him we all went out for dinner together and I made an effort to be open-minded and not fly into ‘protective BFF’ mode straight off the bat. I was friendly and polite and asked plenty of questions, but he was just… unkind.

He was incredibly pretentious and considered himself intellectually superior to the rest of the world, and every time he spoke to me there was a mocking undertone.

Watch: Mamamia staff debate whether cheating is emotional or physical. (Post continues after video.)

I could see Kate was enamored and he seemed to make her happy, though, so figured Sam and I just hadn’t really clicked. That happens sometimes.

But fast forward a year or so and nothing had improved. I’d had Kate and Sam around to my house for dinner, gone on big group holidays with them, and joined them for countless games nights, movies and drinks.

No matter the situation, Sam would always find a way to undermine me for his own enjoyment. It was subtle, and usually buried in his famous “wit”, but I had a radar for it. Kate understood we weren’t on the best terms but I tried not to let my true feelings show. It wouldn’t have aided anything; plus, she was so happy with him.

Making matters worse, Sam had become increasingly controlling of Kate. Trust me when I say my best mate is a strong, successful, whip-smart woman, so I was stunned when she confessed to some of Sam’s more paranoid antics.

He tried to stop her from hanging out with her platonic male friends because he was convinced they’d had ‘a thing’ in the past. One night, when she was dining out with a mutual female friend of ours, Sam was so sure Kate was lying about who she was with that he drove into the city to find her.

He spent more than an hour driving around and scanning the streets to see if he could find her. Kate knew this behaviour was off and she’d always call him out on it — prompting an argument — but it infuriated me that he felt entitled to act like this.

"Look, I know how that sounds, and I know it's crazy, but that's the worst of it," she'd promise, seeing the alarmed expression that must have been painted on my face. "I've told him it's not on. We've spoken about it."

So, back to the Whatsapp message. Kate and I went out for drinks, and of course the conversation was dominated with breakup talk. Like anyone would, especially when gin is involved, Kate spent a lot of the night mouthing off about Sam. Through tears.

"I can't believe how insecure and ridiculous he was," she said. "It's pathetic. I feel so drained. But I don't know if this is the right decision."

Emboldened by one too many G&Ts, I decided to open the valve on almost two years' worth of withheld criticism. "Yeah... look, I couldn't stand him. I'm sorry, Kate, but he was a dick," I blurted out, not actually sorry at all.

"You're such a smart person, and you're so great, and he was a pretentious twat with a massive ego. You can do so much better. I just can't believe you stayed with him for so long. He is not a good guy." (Post continues after gallery.)

A lot more was said, but the details are fuzzy (gin, remember). I recall Kate being taken aback at first but then nodding sagely as I continued my passionate tirade. She trusted my opinion, and now that they'd broken up I figured there was no harm in being honest, even if it was a little too honest.

For a few happy weeks, I had nothing to worry about in that sense. Kate was heartbroken, but we made an effort to catch up regularly and I did my best to take her mind off things. I quickly deleted Sam from all my social media account and looked forward to a life where I'd never have to interact with him again.

Then, a few days ago, another message arrived in my inbox.

"I just spent the afternoon at Sam's. He wants to get back together."

I winced in frustration. I didn't really know how to respond - having told Kate exactly what I thought of Sam, in no uncertain terms, where could I possibly go from there? "Right. Wow. Surprising. But is that what you want?" I eventually tapped back to her.

"I know what you're thinking. But we've been talking for a few hours and things will be different. I think I want to get back with him," Kate responded.

Now it's officially back on, and I'm not really sure what to do. It's only been a matter of days so I haven't seen them together yet, but my birthday drinks are coming up in a weekend's time and Kate is bringing Sam. I have a feeling it's going to be awkward as hell and don't really know what to do. Plus, Kate and I aren't as close now, she seems distant and I feel like it's all because of what I said about Sam.

Did I break a cardinal friendship rule by telling Kate my honest thoughts? Or is it a best mate's duty to be painfully honest about these things? I guess I'm about to find out.

Have you ever been in this situation? What's your advice?

*Names have been changed