This is seriously one of the stupidest questions I've read on here.

Is it absolutely necessary to maintain a friendship with this guy? Really?? If you value your SO maybe don't go on double dates with your ex bf's, fwb's etc. In general it is probably not necessary to maintain relationships with exes to the point that you are socializing with them and current SO. Conflict of interests and just inconsiderate to the person you are ACTUALLY dating. What is your attachment to this guy Op? He is just some guy you used to fuck. WHY get together with him and current BF?????

Even if you don't disclose it, if either of your SO's have even half a brain, they'll sense the history anyway.

Sometimes its the thing which people are trying hardest to hide which they reveal the most.

That just sounds so uncomfortable to me. Why on earth would you even considerate it? He wasn't even a serious boyfriend, he was a f..ling!

it doesn't sound like you have enough in common to make for an entertaining night so I wouldn't bother.

If you actually did agree to a social meeting w/each other, plus your current partners, it would be sort of like lying if you didn't disclose to your new partners what you two shared in your pasts.

Sure, you could do it & see if you could get away w/it, but it seems deceptive and no one wants a relationship based on that.

So you would have to let your current S/Os know the deal. And once they did, it would be hugely awkward. Tenfold.

Best to can the idea altogether. I am sure you have more than enough "friends" you can socialize with than this guy.