K2TOG, I hope your crappy coworker quits. We do luck out sometimes
This person quitting really changes things for the board. Her organization provided the funding. She's said that will continue, but I wonder. It's a really weird sort of relationship between her, her org, and the board. In a way, our board is an offshoot of her org. Without her org, we don't exist, at least not in the way we exist now. Her quitting was an announcement that she will no longer go to any of our meetings.
I haven't decided if I am going to quit this board or just become a sort of inactive member who only shows up to a third of the meetings like most of the other members. I *have* decided that I am not going to volunteer to do anything else for this organization that isn't 100% fun (i.e. attend events I am interested in, nothing else).
I don't want to quit just yet because there is a party I want to go to in May

Technically, I can go just as a member of the organization and not a board member, but one of the reasons I joined the board was because they have better access to information than the regular members. I was hoping I could help improve communication to general membership, but Ms. Bossypants had her own ideas about that, so I dropped it. I think she is still going to control that piece.
The board is one of those things that looks good on a resume, so most of the 'volunteers' seem to have signed up just for that reason. Unfortunately, that group of volunteers was in the majority and chose the initiatives for this year. I have absolutely no interest in working on the set of initiatives we wound up with. It's sort of like the board is split into two groups: 3-4 of us who are interested in X and 12 who are nominally interested in Y but who don't show up or do anything. They just outvote the rest!