It doesnt really matter what they thought of you, what does matter though, is what you think of yourself and your stammer. Do you come out of the situation saying, "Oh no, I messed that up completely, Fuck!" or, "You know what, I stuttered a bit but, at least I gave it a go, and next time I'll improve on it!". In overcoming your stutter, or fear of stuttering, you've got to have a positive mindset about it. The more negativity that builds up, the more you'll feel that humiliation/guilt/self-loathing, and that will only increase your anxiety around speaking.