Jayhawk and MSNik have given you good responses - they are faithful companions of many of us here.
"Cog-fog", as I've seen it referred to here, is very threatening to all of us who are trying so hard to continue working in whatever job we hold. A few friends at work know about the MS, but I don't talk about those erratic moments of confusion or weakness that occur at work - I just keep doing the best I can, taking extra steps to double check my accuracy, saying prayers of thanks for my successful days, and praying sometimes to ask for the continued strength to do things the harder, but better, way. I'm a teacher, and feel blessed to be given the strength that allows me to help my kids. Stay strong, and say thanks often!