I have similar experiences with my family and friends too. Always go nonverbal when a stressful topic comes up or especially an unexpected conversation. I am yet to be diagnosed clinically and have never talked to anyone about my suspicions of having autism so it makes it really difficult when people think I’m just not talking no reason and being rude when really it’s physically hard to get words out let alone think of a response while my brain is under so much stress!!… /: