I really need help dealing with my mom?! im thirteen and a girl:'(i?

im thirteen and a girl:'( i just cant talk to her without both of us getting really mad, and my parents are divorced and my cousins on my dads side of the family are getting married in florida in less than a week but my mom wont let me go and she wont give me a reason. i think its all because she doesnt want me to grow up and i hate it but what can i do!? tonight i talked to her about it and i was calm until she got all mad started saying the same thing over and over 'you cant go because i said so'. she always says that or something of that nature and when she does it over and over it makes me so freaking mad i want to kill her. soon we were both sceamimg our heads off, both threatening to hit each other (her first!!) and i know it was stupid of me to yell but i was getting so mad i just couldnt help it which is what always happens and tonight it got so bad that i cried.. and felt so weak... i hate that feeling, too! i wasnt crying because i didnt get to go but because she is so horrible to me and i dont know what to do... x'( also because now i have to go tell my dad she said no which will make him so freakin mad and i dont want to deal with it cause idk how, i really need help, i called mom when i got invited and she said 'okay' so i thought she meant that i could go but apparently not and now idk what to do because my aunt already got me a hotel place and everything aand i hate to put them down now!! plus i really wanted to go because a lot of the time were there we would be on the beach and i totally wanted to go cause that would be awesome. but no because my mom is awful... she hates me and i hate her, she.just hates everything about me, especially the fact that im growing up and shes so mean about it too. x'( once she screamed at me,'WHY CANT YOU BE MORE LIKE YOUR COUSIN AMY?!' and that made me so freaking mad and sad because amy is my cousin about my age, and eveything about her is ssoooo perfect. perfect grades, perfect looks, perfect talents x'(