You're an adult and I don't think you should have to ask for your family's permission before expressing yourself. You don't represent them, only yourself. Yes, sometimes we mis-speak out of anger and regret it, but sounds like your uncle was a real SOB and it's natural that you were angry. Maybe it's a good thing that someone said something. I don't think it sounds like you did anything enormously bad. Try not to dwell on it, as you try not to dwell anymore on your uncle. Perhaps a message to your cousin, explaining yourself or apologizing or expressing your sympathy, would help make you feel better.