Dear Abby: Long story short: very good friend of mine starts up a band - cover band, 60's-80's tunes. I agree to sit-in at rehearsals/auditions to help him out. He wants me to join, and I finally tell him that I will but only IF he finds two good singers. Well, to my surprise, he does. So, now I'm committed, and he's booking the band. Suffice to say that the band has some weak spots, and it's not a project that I want to continue. I should never have agreed to participate, but that's water under the bridge. Looking for advice on how to get out of this delicately, while preserving friendships with a couple of the members.