that is in your mind. not your stutter but the "I could fire myself" part. that's your subjective judgement. you did not get fired. and that is the objective truth. as healthygamer recently said about overthinking and rumination, focusing too much on feeling embarrassment makes you blind to what's going on. you need to get used to your own voice, and be able to watch your own secondary behaviors. it's part of getting to know your body.