It's really up to you actually. I've stated in the other threads that I've gone through a similar situation (I wasn't the gm, but I had to act as a gm at one point when my gm wanted to 'explore' the guild world out there. I stayed behind trying to hold the guild together). If you think that your guild is worth saving, I'd shrug things off and move on. With different sets of ppl, except for a handful of faithful ppl who stay behind and have the same commitment as you do to revive the guild, and start over. It is possible. There are big guilds out there that used to be some of the strongest and most respectful guilds, and they had their time of going down the hill. And recently a few ppl wanted to revive them to their previous glory.
But if you think that bad atmosphere lingers in the guild and gives a bad aura to the entire guild beyond repair, then it's probably time to tell the entire guild that you'd dissolve it. And start a brand new guild. You may still carry some of the old members with you (I'm in that situation with one of my guilds right now, where my gm started a new guild). Close the pages of the old history, and open a brand new history and image with the new guild. Starting fresh energizes the members of the old guild that come with you as well.
On another case, my other gm just decided that he was done with guild responsibilities, and prefered to join another guild as regular member/officer. Whatever you decide to do, good luck!
If you need a guild I'm in McRaging and you could join it if you'd like 
