My mother is a liar?

Okay. So my mother is a liar, and she is one of those people that can never admit she was wrong. I was supposed to pick up my grandpa at the hospital. She tells me not to leave yet and I said fine. So I go up to my room, and then my uncle shows at my my house expecting my grandpa to be there. So I go to my mom and say well now what are we supposed to do? She goes why do I have to come up with a plan? I told her because she was the one to tell me not to go get him in first place. She answered, "I never said such a thing." SHE IS A F***ING LIAR! (And mind you this isn't the first time she has done something like this, so now I was just really pissed) So she comes into my room and I'm explaining to her that she did tell me to not get him, and that she lied. Well, she got pissed and almost slapped me and took my phone away and grounded me. EFF THIS. I honestly cannot take her anymore. My friends never want to come over because they are afraid of her. She controls my life and I hate her