Yeah, I know, it is helpful.
I wound up talking to C's SO who kicked him off his chat to be reassuring at me, and basically being like no, this isn't going to be fixed in a day, but it's also very highly unlikely to have been ruined in one. Take a step back, breathe, talk, and don't panic.
I think I really need to try to tell him, because he might have misunderstood, that just because C and I are glad that us liking each other is out in the open, doesn't mean we're going to rush into anything, even if both our SO's were 100% okay with it. Even for our own sakes taking things slow is important, and we're both okay with the idea of just being friends for a while. Whatever else we just enjoy hanging out, I guess we're more friends who have acknowledged that there is the potential for something else.
Does that make sense?