Everyone puts on a front to some degree. The super confident articulate people are trying really hard to seem that way. Every one has things eating at them to some degree they just aren't as obvious as yours. I doubt that guy was trying to be offensive. The best advice I ever got was to just act like your stutter doesn't bother you. No stutter is truely ever cured so you have to learn to live with it. If people think you are OK with your stutter they usually are as well. I have a safety critical job where leading work groups and talking on the phone is part of my job. I hate my stutter with a passion and do my best to reduce my anxiety to make me as fluent as possible. Only people close to me know this Everyone else thinks I'm much more OK with my stutter then I am because I act that way. Everyone at my work eventually learnt I know my job and I do it well. The stutter is just part of me and they accept that. No one at work seems to care or talk about my stutter and I just do my job. It might take time to reach a level of comfort at work but you will get there eventually. Just stick to it mate