Last night I refused to say "yes ma'am" to my boyfriend's mom and the backlash from my man was ridiculous

So my boyfriend is a 35M and I'm a 34F. We've been dating for 11 months, living together for 3 months. He comes from a fairly traditional conservative background, and so do I. <br><br>In my culture, it's customary to treat your elders with respect and to use terms like "sir" and "ma'am" when speaking to them. However, I only say these terms if I chose to. I have a disability that often makes me flustered and unable to think of the right words. So if I'm having trouble finding my words, no "sir" or "ma'am" will be coming for a while.<br><br>So last night, my boyfriend's mom was in town and we went to dinner at a nice restaurant. During dinner, I had done absolutely nothing wrong. I was respectful and courteous. I said "thank you" to the waitress. My boyfriend was being his usual sweet self. His mom had made the reservation for us so we got a nice table with a view. I tried to make conversation but the mom clammed up and was short with me.<br><br>After we were done eating, I excused myself to the restroom and my boyfriend followed. He was fed up with me because I didn't address his mother as "ma'am" each time I spoke to her. I told him it doesn't make sense to address her as "ma'am" every single time I say something to her. Plus, I said "please" and "thank you" multiple times. He was horrified that I didn't say "yes ma'am" and that I kept a calm tone when I spoke to her. He told me that I came off very arrogant and that I "seemed intentionally dismissive and rude".<br><br>Let me reiterate, I was nothing but respectful. I didn't raise my voice, interrupt, or talk over anyone. I always addressed my boyfriend by his name and I said "thank you" to the waitress more than once. <br><br>Just because I didn't say "yes ma'am" constantly doesn't mean I was intentionally being rude. I told my boyfriend this and he had a huge melt down. He told me to go home and that he couldn't be with someone who disrespects his family. I reminded him that I'm also an adult in my 30s and that I expect to be treated as an equal. He told me to stop making excuses for myself and to be more humble.<br><br>I left the restaurant, went home and cried. I've been wracking my brain trying to figure out what I could've done differently. Was it really that big of a deal that I didn't say "yes ma'am"? I feel so stupid for thinking I'm an outsider looking in. My boyfriend's mom never liked me. She made back handed remarks when she first met me, saying that I'm "skinny and don't eat much". I'm not skinny, I'm actually overweight but she made this comment in front of my boyfriend and he made excuses for her and said "she's just that way sometimes".<br><br>We had a huge argument last night and I don't think he's ever going to call me or apologize. He thinks he's 100% right and that I'm just making excuses for my behavior. I'm seriously done and over this. It's just the principle that I can't be wrong for not saying "yes ma'am" constantly.