Am I being emotionally abused?

My family is made up of two younger siblings a brother and sister and my mom. My dad got kick out of his girlfriends house and is living with us now. He seems not to like me very much. He calls me fat and makes fun of me. My mom and siblings sit there and laugh. Im always doing chorse and things for people. I just clean the kitchen, the living room, the bathroom and my room even though i share it and ny sister makes the mess. Im to go in my room when i am done and sit at the edne on my bed. Right nw all my stuff is in my moms room. One more strike and i throw it all away. i used to have a journal but my sister gave it to my mom and dad. They read it and now i am grounded till the end of summmer for writing down my feelings. My grades have slipped. My mom used to be the only on ding this but now its my dad to. I really try t get my grades up but whenever i come home and show them they say SO. School right now is my haven and i never want to be home. Sometimes im not aloud to eat and they eat in front of me. Most nights i cry myself to sleep and think abut wheather to run away or thoughts of suicide. Ive tried to tell my grandmother and she wants me to see a therapist. Now i am no longer to see my grandmother because "What ever happens in this house stays in this house." Im really confused and scared. I decided to do this. Please help.