I appreciate that experience of stuttering and how we live with it is subjective. But I object and completely disagree with calling it a “disability”. It’s only a disability if you allow it to be. If you hide away from the world and not even try to speak to anyone you are just making your stutter worse because you are actively telling your self (your subconscious) that you can’t do it. And in then end you stutter. Also you ex boss is an idiot. And even if you did get the promotion he is not a person you want to work for. Don’t take his actions to heart or let it stop you for living your life and doing the things you want to do! He is just one bad boss, next one will be different.