Uninviting guest?

So I'm in a bit of a sticky situation. I have two friends who dated for over a year, but ended up having quite a messy breakup. Initially we wanted to try inviting them both to our wedding, since we knew & were friends with them both before they started dating. However, as time has gone on it's become clear that they won't be able to coexist peacefully for the duration of the wedding. I've also learned some details about their breakup that make it clear that it was worse than I originally thought.

We know who we should invite and who we should cut based on who we are closer with. I'm just not sure how to go about uninviting the other party. We already sent him a save the date and I talked to him not long ago about when invites would be sent out. I want to be as tactful as possible, while making it clear that we don't blame him for the drama and leaving it open for our friendship to continue if that's what he wants (tho I understand if that's not possible; I definitely messed up here).

Has anyone dealt with a situation like this before? Thoughts on how to go about this?