mom fat shaming me in public

so im always insecure about my weight and im really obese, having fatty liver and stuff. i try my best to resist those junk foods. so today we were out in public and i saw a shop selling really good fries and i asked my mom if we could get them. she literally yelled at me in public so loudly everyone around us could hear. she yelled about how fat i am and literally yelled out my weight-induced diseases and said i should be ashamed, calling me a fat fuck and all that. she even yelled at me and lifted my shirt up in public forcefully to show how fat i was, not caring everyone was watching. it was so embarassing i couldnt even make eye contact with anyone for the rest of today. i cried alone after i came home.
i know this is really long but i needed to let it off my chest, i dont know what to do.

Edit: what pisses me off more is that my mom is acting completely normal right now, as if nothing ever happened. she keeps asking me "what's wrong, you seem a bit sad". its beyond infuriating. also, i was trying to talk less to my parents since that incident, and my mom commented "look, he's so lazy he doesn't even want to talk", and my dad added "yeah, thats why he's such a fatass."