Cheryl,
I have not been on this board for long, but you seem to be so helpful and kind. I can't imagine that you have any reason to feel guilty about blowing some steam off today. I am so sorry that people made you feel uncomfortable. In this day and age there is really no excuse for that. I have been having some pretty crabby moments myself when people don't seem to act as I believe they should. For the most part I can't stand the pitying attitude - I find it totally destructive.
At least YOU know that you are not defined by your cancer. You are as much yourself as always - maybe just a bit stronger and a lot more enlightened.