In college, I had a fairly close knit group of friends that I played games with pretty regularly. That group primarily consisted of 4 people, myself, Alice, Bob, and Sam, with others joining depending on who everyone was friends or roommates with at the time. Alice and Bob started dating after a while, and myself and Sam became pretty close friends, and that was the situation when we all graduated.
It's now been a couple of years, and things have changed quite a bit. Alice and Bob moved out of state for grad school, while myself and Sam stayed in our college town. Since college, Sam and I have stopped being friends for various reasons, and I believe Alice and Bob have stopped dating, though I have been unable to confirm that. I'm also reasonably sure that Bob/Alice have the same level of ambiguity over whether Sam and I are friends now. I don't really hang out with the peripheral friends anymore, because for the most part they were all everyone else's friends or roommates, not strictly speaking mine, and our interests drifted apart over time. So, these days, the old friend group really doesn't exist in the same way.
Bob is coming back to the state for Christmas this year, and messaged me to see if I wanted to get people back together to play games. I'm not necessarily opposed to the idea, but I don't want to do the social lifting of trying to plan it, especially with people who are disinterested in playing games and have blown me off in the past. At the same time, I really don't want him to invite both me and Sam in a group chat with everybody, or anything similar, because of how awkward it would be. So I want to try and figure out what the social situation would be if we did play, to try and head off the problems at the pass.
So, given that, my question is twofold: how can I tactfully ask Bob whether he's broken up with Alice, and if he would want her to come (is this even appropriate to ask? I have 0 experience here...), while also explaining to him that Sam and I are no longer friends, and that he cannot invite us both to any get together?