This is Sparta and I Feel like Punching Something I'm so Mad?

Okay so I am PISSED at my grandparents! My grandma like hates us or something and same with my grandpa! To start, a while back I was stuck and their house right after my tonsils were taken out (I was stuck there cause of a family emergency) and I was supposed to be bed ridden for two weeks. My grandma called me a fricking SLUG for lying in bed!!!! I was soooooo mad I was tempted to scream "okay fine I'll jump around like a crazy maniac and end up in the ER bleeding to death because my scabs will fall off and I'll be dead and it'll be your fault!!!!! Plus, it'll ruin your perfect little rug that care about more than me so HA!!!!!" but I didn't instead I just ignored her and stuffed my head under a blanket and cried and cussed. They kept on trying to get me to go to school and jump around like I DIDN'T just have surgery!!! I am really mad and I need help because this weekend I am supposed to have a cookout with them but I really don't wanna and neither does my little sister (she's mad because my grandma said she has no manners when she says please and thank you all the time but ironically, my grandma NEVER says please or thank you). I really need help with this one. And please don't say I'm a 'cry baby' because there are so many more reasons to be FURIOUS with them (they yell a lot, are stuck up, brag about my bratty cousins like they're better than us, tell us to put our dog to sleep, butt into our business, etc.). Also, if I don't get help I might end up punching and breaking something the moment they make me up set so please please help and thank you very much!