Mom fat shames me.. what do I do?

To start off I am an 18 year old girl and a senior in high school I’ve always been insecure about my weight because I am a bit chubbier than the girls my age. But lately I’ve been comfortable with my weight but that changed. To start off I found out from my little sister while on a walk with her that my mom has been secretly fat shaming me.

My little sister told me once when I went outside to practice she heard my mom say “OP needs to exercise.” Prompting my little sister to go “mom!” And my mom replied with “what it’s true.” And for context my mom isn’t skinny either and yet she mainly attacks me for my weight. At dinner it’s always subtle comments I’ll get my food and when I go back up for another helping she’ll go “geez!” Or say things like “you better eat all of that.” And it discourages me from eating. It’s always me she does that too. So whenever I am with someone or my grandma at her house and I accidentally take too much I get scared she’ll make comments but my grandma doesn’t make any comments or digs at me.

One time my grandma told me that my mom was talking to her and she said “I wished OP would stop drinking pop and drink more water so she doesn’t get diabetes.” And it made my grandma mad. When I was little my mom made a comment about my weight and said it wasn’t normal for a little girl like me to weigh that much. She later apologized but that comment has always stuck with me. Once on vacation I weighed myself for fun and didn’t think much of it until I found out later that my mom said “I weighed myself and I weight 200 pounds I need to diet. I think OP and I weigh the same.” Idk why but it hurts hearing my mom make these comments. I want to tell my dad or grandma. But I don’t want to because I’m scared that my mom will get mad at me. And I don’t want to tell my grandma because I’m scared both mom and dad will get mad.. I’m scared of even eating tonight… what do I do?