To Threesome Or Not To Threesome

Ok, so here's the sitch:

My wife tells me that one of her coworkers, who is a girl, is very in to me. I guess they got to talking and her friend ended upaskingabout a threesome. My wife says she's down because it's a friend of hers and it's kind of on her terms... Ok, so all this sounds well and good, don't get me wrong, but here's the thing: this would be the fourth time I've been asked to participate in a threesome, however, the first three times were from my younger years and it would have been two dudes and a chick, and I declined all three.

I declined those times because I just wasn't quite sure if performance would have been an issue with another dude in the room. I'm not homophobic or anything like that, but it's just I don't know that I could keep things up if ya know what I mean. So fast forward to now and this is a different deal, two chicks and me. But if I accept, does this open Pandora's box and am I then obligated to throw a threesome at my wife with another dude? Cause if that's the case, I don't know if I'm down for that.

This is like one of those things where it's on the bucket list, but at the same time, I don't want to deal with opening a can of worms.

Anyways, I though I'd get some takes on this. Thanks in advance.

And my apologies if this is not the appropriate board for this, but it seems like the closest one for this type of thread.