Belinda,
I think it's very telling that you have sent this letter out often and only received negative replies twice. It's very similar to twenty people telling you they liked your presentation and one person saying they didn't - you dismiss the twenty and dwell on the one (I do anyway). I work at a college and I go batty at the number of students who don't read the directions. I think your response was appropriate. If someone attacks you like that you have every right to respond. There is no need to feel guilty about giving him as good as he gave!
Maggie
PS Thanks for the work you do with that group!
