There’s been multiple times where I choose to not express myself over my speech impediment. When I get into verbal arguments, I usually back out or drop it knowing I cannot express my self. Same if I disagree with something or during group projects. But your situation with your uncle genuinely seemed rude and unfair. Guessing your uncle is not familiar with your stuttering/impediment? I’ve been around my uncles and aunts for long enough to where they know I have a speech impediment, and they usually fill in the blanks for the words I cannot say or finish.